3D Printing for Chickens (Feeders and Other Accessories)

Have a 3D filament printer? Want to make some useful things for your chickens? Then this article is for you! 3D printing lets you create custom shapes out of plastic materials, potentially quite unlike any premade products on store shelves. This article is broken into three pages:

• About 3D Printing: some basic things about 3D printing with a focus on filament-based printing, including some important terminology and general things to be aware of when printing for chickens. Start here if you're wondering about getting into 3D printing or if you're very new to it.
• 3D Printable Projects for Chickens: several chicken-relevant projects you can print right now, most of which are related to feed/water - but also including the little chicken design shown as a print-in-progress in the title image.
• Designing 3D Printable Objects for Chickens: a brief overview of 3D modeling software and design considerations for making chicken-safe, functional objects.

FDM Printers, Slicers, and Filament​

There are a number of different processes and categories of equipment that fall under the broad umbrella term of “3D printing.” From the standpoint of entry/hobby-level equipment for the average consumer, there are two main categories of 3D printers: filament deposition modeling (FDM) printers and resin printers. This article and its associated functional projects are for FDM printers only. Do not use a resin printer to make functional objects that will be in contact with chickens or other animals – the materials are potentially hazardous.

FDM printers work by melting plastic filament and extruding it into a new shape. The input filament is typically mounted on a large reel and feeds into the print head. The print head moves around and builds up an object one 2D layer at a time, where each of those layers has some small thickness to it. Each layer is produced much like you would draw the corresponding shape: laying down a perimeter, also called a wall, and then drawing lots of little lines to fill in larger areas. The furious scribbling inside the perimeter is called infill. The more infill, the more material required and the more solid the object.

The object being printed is initially represented as a digital 3D model, usually a file ending in .stl. These files contain maps of vertices and edges defining a mesh for the exterior of the object, but the printer needs to know how to build that mesh’s shape in terms of horizontal layers. This is where a piece of software called a slicer comes in. There are a number of freely available slicer apps: Prusa Slicer, Orca Slicer, and Cura to name a few. Some brands also have their own slicer programs specifically tailored to their machines. As the name implies, a slicer “cuts” the mesh into a lot of thin layers and produces machine instructions for how to print each layer. For FDM printers, the resulting instructions are printer-specific and saved as a .gcode file. Slicers typically offer a variety of settings to change the quality and internal structure of the print. Slicers also have the ability to add extra structures called supports, which are necessary if you have difficult-to-print structures like large overhangs where the filament may otherwise collapse. All of the projects attached to this article are support-free, meaning they don’t require supports to print well in their default orientations.

There are many types of filament for FDM printers. Only use a food-safe type of filament like PLA or PETG for anything that will be in contact with chickens or other animals. PLA is the easiest material to print with, but PETG is supposedly more resilient for outdoor usage. Both PLA and PETG are relatively safe to print inside a home; other materials can create quite hazardous fumes during printing. Clear PLA and PETG are both safe for use with chickens, and most plain colors of those materials are too. Avoid special/fancy filaments like PLA+ or silk PLA for use with chickens or other animals. Also avoid filaments that have inclusions of other materials (wood, glow-in-the-dark compounds, glitter, etc.).

Air quality caution: print only in a well-ventilated area, even when using a relatively safe material like PLA or PETG. Do not use an open-air printer or one that vents directly into the room for any significant length of time without at least partially opening a window nearby. VOCs and CO2 can both build up quite rapidly in a completely closed room with an active printer (something the author has directly tested with a CO2/VOC meter). If you are unsure how effective your ventilation is, you can buy a portable CO2/VOC meter to monitor the air quality in or just outside the room. Never print in a room with pets. Use caution in proximity to birds and aquariums, even if they are not in the same room as the printer.


Other things you may be wondering (FAQ):

• Why are resin prints potentially hazardous for chickens? Consumer-grade 3D printing resins are not considered a food-safe material even when cured. Resin printers are great for printing highly detailed ornamental models, but they should never be used to print objects that animals will be in regular contact with or objects for use with food/water. Some resins claim they are safer by being "plant based" or simply "low VC"; while some of those products can indeed produce fewer VOCs in their liquid state, the lack of safety with food and water remains even for the cured product.
• Do I need an expensive machine to print useful things / the designs in the ZIP? No, although to some degree it depends on what you consider “expensive.” All you need is an entry-level machine with a big enough build plate. Suitable machines range from around $200 to $500 at the time this article was written. Some 3D printers get significantly more expensive, such as $1,000+. Those printers have perks for sure, but you don’t need anything in those upper price brackets to start making useful items. Really the only category of printer to avoid are those with exceptionally small build plates (there are some super-tiny printers on the market aimed purely at making small toys/trinkets).
• Is my FDM printer build plate / print volume big enough for the projects in the ZIP file? To print support-free, the biggest projects here require a build plate of at least 220mm x 180mm and a printable height of 200mm high (or 8.7” x 7.1” x 7.9” in inches). The feed scoop is the tallest design (200mm), and the double grit holder is the widest/deepest (220x180mm). A build volume of 180 x 180 x 180mm will be able manage a few of the projects, but a build volume of 220 x 220 x 220mm is better. You can try reorienting projects to fit on smaller build plates, but changing the orientation may significantly decrease the quality of the print and may require the use of supports (all of the designs are support-free in their default orientations). Not all projects scale up/down well; this is noted per-project.
• What printer/filament/slicer did the author use to make the example prints? I used an Anycubic Kobra 2 Plus with a 0.4mm nozzle, various non-toxic, solid-color Sunlu PLA filaments (clear, white, etc.), and a single reel Sunlu filament dryer. This printer has a 300x300x350mm build volume. All pieces of equipment used are very much budget, entry-level options for medium-sized FDM printing. This should only be considered a point of reference only, not a product recommendation. I used both Prusa Slicer and Anycubic’s own slicer; both slicers are free.
• What makes one design “easy” to print while another is “difficult?” Different combinations of models, particular printers, and filaments require different slicer settings for parameters like print head acceleration/speed, temperature, fan activity, and so on. A model is “easy” if the default settings for the filament/printer in the slicer are likely to work just fine for the intended purpose of the model, and if small imperfections in the finished result won’t harm its utility. Another model will be “difficult” if the settings have to be tuned more carefully to the particular printer, filament, and model.
• Do I need to do any post-processing on my prints to make them safe for chickens? Potentially. You may have excess material that needs removal, such as stabilization brims at the bottom that don’t tear away easily, globs from the print head starting a new layer, rough edges, or even edges or corners that end up a bit sharp. A hobby/utility knife can be used to remove excess material like brims and to clean up or smooth edges. A deburring tool can also remove brims and smooth edges and is somewhat safer to use than a knife (although not entirely safe – you can still drive a deburring tool’s blade right into your finger!). Sanding is also an option to smooth layer lines at edges. Use caution with any kind of electric sander or rotary tool – both have the potential to melt the plastic and easily destroy the outer wall.
• How can I clean 3D printed feeders/waterers? First, try to minimize porosity in your prints with settings in your slicer. Smooth surfaces and minimal gaps into inner portions of the model are very important to create an easily cleanable surface even if it has a texture (which nearly all 3D prints will – some texture is unavoidable without post-processing use of fillers and/or sanding). Smooth top layers with no gaps and excellent layer-to-layer adhesion will minimize porosity. Second, if you can simply wipe it clean with a damp cloth, that is ideal. For more thorough cleaning, printed parts can be hand-cleaned with soap, water, and a soft sponge. Avoid fully submerging the part if you used <100% infill. Avoid abrasive scrubbers that may leave scratches. Let feeder parts air dry VERY thoroughly before putting them to use again with feed. Avoid putting your prints in the dishwasher, since the heat from a hot wash or drying cycle has the potential to warp the more commonly used materials (particularly PLA).
• Isn't PLA biodegradable / not UV-resistant / not heat-resistant? PLA is only biodegradable under very specific conditions - don't throw it in your compost pile and hope that it will decompose. This means it also won't break down rapidly due to being in a chicken run. The outdoor resiliency of PLA is a subject of some debate on the internet. Most of the complaints about it are centered around color fade, and long-term toughness tests often subject the object to some kind of serious falling damage that isn't really normal usage. Many plastics eventually become brittle when sitting in high heat and direct sun for a long time. The longevity of your print will depend a lot on the conditions it is exposed to. To maximize the lifespan of any 3D printed object, it's best to keep it out of direct sunlight and also not leave it sitting in intense heat. PETG is a bit more heat resistant and supposedly more UV-resistant too, but also significantly harder to print. Both materials can warp if exposed to very high heat, such as in a hot car in the sun or in a heated dishwasher - neither of which is comparable to the conditions of a chicken run.

This article's main page includes an attached ZIP file of 3D model files (stl) for several chicken-related 3D printing projects. Each design fills a particular need I’ve found in my chicken-keeping experience that wasn’t met by the regular market of plastic things. Here is a direct link to the ZIP file of project stls:

Download 3D-Printable Project Files

Reminder: only use a food-safe type of filament like PLA or PETG for anything that will be in contact with chickens or other animals! Stick to clear or basic solid-color filaments. Avoid silk PLA and PLA+. Avoid filaments with inclusions of other material like wood fiber, glow-in-the-dark substances, or glitter.

An important prerequisite to diving into these projects: make sure you have a slicer app installed, have opened it, and looked up how to load the right settings for your particular printer and filament. Also make sure you know how to load new gcode files onto your printer. These steps are different with every slicer and printer, so it's something you may have to google search; there are simply too many different possible factors to cover this basic step in detail here. Manufacturers typically have instructions and slicer config files available online. You do not need to know how to add supports to print any of these projects.

Each project below is support-free, and the stl files are already in the orientation the author deems best for printing. The stl files should also import at the correct scale. So, all you need to do is import a .stl file into your slicer, dial in any special settings noted, export gcode, and get that gcode running on your printer (often done via USB stick but some printers let you do it over your home network).

There are 6 included projects:

1. Ornamental chicken model – ok this one isn’t functional, but it's a great way to test slicer settings with your printer.
2. Simple/small feeder – a small feeder design for small spaces. It has a high back and side walls to minimize mess. You can customize the size based on your limitations.
3. Feed scoop with lid – a scoop to keep your feed dry between the bin and the feeder.
4. Weather-resistant grit holder – a big-comb-friendly way to keep grit and oyster shell clean and dry in the run.
5. Rooster-friendly feeder port – a great big feeder port design for great big chicken faces that can’t fit through the readily available feeder ports on the market.
6. Extension cord thru hardware cloth adapter – an easy way to run an extension cord through hardware cloth only when you need it and plug the hole when you don’t, such as for running heated waterers in the winter.

To get the files for these projects, download the ZIP file called 3d_printing_files_for_chickens.zip and extract it (please note the license for these files below!). It contains nested folders labeled by project name. Some projects contain multiple stl files.

3D Printing File License: the stl 3D model files included as attachments to this article are all designed by Donya Quick (the author) and are for personal & BYC use only. Do not upload the stl files to other public platforms without the author’s permission. All stl files are provided ‘as is’ and without any warranties, express or implied.

Project 1: Ornamental Chicken Model​

You know you want at least one of these on your shelf. It's also a good test for new filaments and/or testing slicer settings. Quality issues to look for:

• If the comb looks a lot worse than the rest of the model and doesn't seem to quite line up properly, or if it fails completely and is stringy, you likely have Z-shifting issues. This means your print is getting subtly out of alignmet over time. Sometimes this is just a matter of slowing down the print speed and/or tightening belts. A small amount of Z-shifting is normal and just manifests as a slight sheen difference. Too much and you may end up with holes that expose the interior of the model, which is bad for the other models on this page since it presents a place where water or dirt can get into the model and collect.
• If you see sagging filament lines on the underside of the chest, your printer or filament isn't doing terribly well with overhangs. Sometimes variable layer height will help with this, as will decreasing print speed or adding extra wall perimeters.
• Check the bottom of the feet - the bottom surface should be completely solid and sturdy. Holes, flexibility, or filament strands not holding together well when pressed on means you have some first layer issues to resolve. This can be a calibration issue with the printer, a lack of bed adhesion (try cleaning the bed), extrusion or bed temperature too low (particularly if you have a drafty room and open-air bed-slinger printer), or slicer settings (try going back to defaults if you customized a lot of things).
• The top surfaces of the wings and back should also be completely solid. You will see layer lines if you look at the right angle but shouldn't see grid texture, porosity, or any gaps at all between lines of filament. Gaps and excessive top texture can sometimes be fixed by enabling ironing on top layers, but that doesn't necessarily solve the underlying cause of the texture. Bad top layers can be slicer settings (not enough infill, extruded rows too far apart, etc.) or even a more chronic under-extrusion issue like a partially clogged nozzle.

Print difficulty: easy; even if it shows some of the quality issue above, it's quite unlikely to fail more seriously unless you have more fundamental issues with how your printer is functioning.

Files in the ZIP: ornamental_chicken.stl

Scalable: yes (uniformly) – it will just lose detail as you go smaller and may show some issues with overhangs on the underside of the chest if scaled up a lot.

Recommended material: anything you want! This is, of course, just an ornament.

Recommended slicer settings: it should work with most defaults. This is a good file to test different filaments and printer settings. The example model was printed with variable layer height to improve quality but that's very much an optional setting.

Project 2: Simple Feeder/Waterer​

A minimalist feeder/waterer for use in space-constrained situations. Use this to hold feed, grit, or water* in a hospital/isolation crate or other temporary home a chicken where just a small amount of feed/water needs to be supplied. If using the supplied clip design, note that the shorter, wider end is what attaches to the holes in the feeder. The long, thinner side is intended to snap over bars like in the picture above.

*Regarding water-suitability: to hold water safely and be easy to clean, this container needs to be solid when small or have quite thick walls when scaled up, and it needs to have smooth layers and excellent layer-to-layer adhesion. Unless you live in a dry climate, a filament dryer may be required to achieve the level of smoothness needed (filament exposed to moisture produces a rougher print texture). Any visible gaps due to Z-shift (when layers get out of alignment over time) needs to be addressed post-print before use with water. If you have a 3D pen, you can load some of the same filament to fill gaps or “paint over” iffy-looking spots and then sand own as needed. A soldering iron may be a tempting alternative to correct imperfections, but if the hot end has ever been used with solder that contains lead, then it is unsafe to use on feeders/waterers.

Print difficulty: easy for feed-suitability. Difficult for water-suitability (requires a higher level of smoothness).

Files in the ZIP: simple_feeder.stl. Optionally you may want two instances of clip.stl.

Recommended material: clear or solid-colored PLA.

Scalable: the feeder is scalable to a degree - non-uniformly scalable as well! Stretch and squash it a bit as needed to meet your dimension needs, but pay attention to wall thickness when sacling down. Clips should not be scaled much, if at all (the snap mechanism can easily become too stiff or too brittle), and they may not be able to snap onto scaled versions of the feeder.

Recommended slicer settings:

• If your slicer has a setting like a “precise wall” tick box, make sure that setting is enabled! Otherwise, you may see some odd distortions around the clip holes.
• Set infill to 100%. If you scale up, you can use sparser infill but should increase the number of outer wall loops.
• Enable ironing on all top layers if this setting is available. If the ironing setting is NOT available and you often see small gaps between parallel rows in your prints, then the resulting print will not be suitable for holding water (too much chance of water getting inside the walls, even potentially a full slow leak to the outside, cleaning difficulty, etc.). However, it will likely still be suitable for holding feed.

Usage/assembly: you can use the included printable clip, store-bought small clips, wire / twist ties, or even zip ties in a pinch to anchor this little feeder to either hardware cloth or the bars of a small kennel.

Project 3: Feed Scoop with Lid​

Tired of rain/snow getting into your chickens’ feed on the way to the coop? This scoop will let you slog out into even the nastiest weather with confidence.

Print difficulty: easy but takes a long time (allow 6+ hours)

Files in the ZIP: feed_scoop_base.stl and feed_scoop_lid.sl

Recommended material: clear or solid color PLA or PETG.

Scalable: with caution, but not recommended. Any scaling must be uniform on all axes to preserve the shape of the hinge.

Recommended slicer settings:

• Seam position: aligned or back. For the lid, the “back” should ideally be the front of the lid (try to avoid seams along the hinge).
• I recommend printing one piece at a time.
• If you have had trouble with flat surfaces warping, try enabling an outer brim for both pieces of the feed scoop.
• Optional: enable ironing on all top surfaces. This will help create a less textured, easier-to-clean surface on the bottom of interior of the scoop, although the top of the scoop body may require some scraping to clean up.

Project 4: Weather-Resistant Grit Holder (Rooster-Friendly)​

These grit holders are designed to keep rain/snow out from the back and to a more limited degree from the sides. If water does get in due to condensation, snow blowing around, or just a really windy rainstorm, small drainage holes help the grit to dry out again rapidly. This design accommodates large combs and is best mounted midway along a wall of hardware cloth or welded wire and can be anchored with zip ties or clips.

Print difficulty: easy but takes a long time (allow 6+ hours)

Files in the ZIP: grit_holder_single or grit_holder_double. The double version has two bins to keep regular grit and oyster shell separate. The single version is better for smaller build plates.

Recommended material: clear PLA or translucent white PLA. Avoid dark and/or very opaque colors as it makes the grit harder to see (both for you and for the chickens).

Scalable: NO - drainage holes may cease to work at smaller sizes.

Recommended slicer settings:

• Enable outer brims to minimize the chance of corner warpage. Avoid having inner brims if your slicer allows, since those will be hard to trim away from the hanger loops.
• Don’t use ironing on this design; it prints best on its back, so the only significant ironable surface is the inside of the back wall.

5. Rooster-Friendly Feeder Ports​

Port feeders can be an easy way to keep feed dry when wind regularly blows rain through the sides of enclosures, and they can also stop chickens from digging feed out onto the ground. However, standard feeder port kits for chickens are really only suitable for small-combed chickens. A lot of roosters can't fit their heads through those ports. I got tired of using excessively open feeders to accommodate my roosters, since my hens were shoveling food out at an alarming rate. I designed these ports to reach a balance between allowing roosters to reach into a feeder port while making it not entirely easy for hens to dig in the food.

Caution regarding chicken size: this design is for adult, standard-size chickens. Do not put small chicks in with this feeder, as they would be able to get fully into the port and may also be able to get under the back lip of the port and into the larger container when the feed level is low.

NOTE: this design is not a complete feeder, just the port. You must still purchase or a suitable container and some other materials in order to set up a feeder like the one pictured above.

Print difficulty: easy but takes a long time (allow 6+ hours)

Files in the ZIP:

• feeder_port_front.stl
• feeder_port_back_A.stl OR feeder_port_back_B.stl. My birds preferred design B, but A is more space-conservative for smaller containers.
• gastket_template.stl - useful for mounting the port accurately even if you don't want gaskets.
• (Optional) vent_cover.stl. These are for environments with large temperature/humidity swings that can cause condensation in well-sealed feeders. On larger feeders, use 2-3 of these ABOVE the max feed line (as close to where the lid sits as possible).

Recommended material: clear PLA

Scalable: scale up only. Scaling will change the size of the bolt holes and therefore the size of bolts needed. The bolt holes will become unusable if scaled down much. Scaling down also defeats the point of the generous space for big combs.

Recommended slicer settings:

• You may want to enable outer brims to minimize the chance of corner warpage.
• Avoid having inner brims if your slicer allows, since those will be hard to trim away from the hanger loops.
• Do not use ironing on the back part of the port; it will not significantly affect quality and just slows things down.

Other required parts:

• Flat-sided plastic container of the desired feeder size. The container must be big enough to allow 2-3” space on either side of each feeder port and at least 1” above and below each feeder port. More than 4” of space around the feeder ports may result in having to shake or tilt the feeder periodically to get old feed into reachable areas. Sides of the container intended to have ports can be sloped slightly but must be a completely flat surface.
• 6x M3, #4, or #6 bolts and nuts per port. Ideally use nylon bolts and nuts.
• Drill with bits appropriate to drill holes for your bolts in the plastic container.
• Sharpie or other marker that can mark the plastic container.
• Rotary cutting tool with a small cutoff wheel to cut the plastic container without breaking it. Alternatively, you can drill holes at the corners and use a small saw, but the risk of breaking the plastic will be greater.
• Optional: 5/8” drill bit to allow ventilation holes (only necessary for tight-fitting lids in areas with significant temperature/humidity swings to avoid condensation inside the container)
• Optional: silicone mat or other food-safe gasket material to cut gaskets from to sit between the container and the feeder port front.
• Optional: small wrench to hold the bolts while you drill them in (just makes the process faster/easier and gets a tighter seal if using a gasket).

Assembly and usage:

• Use gasket template to mark two things for each feeder port you want to install: (1) the location of the large hole in the middle and (2) where the bolt holes are. The gasket template has an indented triangle on the top edge (the triangle points "up") so that it can be oriented correctly.
• Drill out the bolt holes next to avoid cracking the plastic later. They sit very close to the large hole.
• Optional: drill out 5/8in holes for vents.
• Cut out the main rectangular hole for the feeder port. Err on the side of cutting very slightly larger than the marked line. Check that the port’s back end can pass completely through the hole before continuing.
• Wash and dry the container to remove dust and bits from the cutting. Your container should now look something like this:
  
• Optional: use the gasket template to cut gasket and mark locations for the bolt holes on a silicone mat or other suitable gasket material. Make sure the feeder port back end can pass all the way through the hole in the middle of the gasket. Make tiny cutouts where the bolts will pass through. One way to do this is to cut a very small X and then trim the triangular corners.
• Install the feeder port front with bolts and nuts. If using a gasket, put the bolts through the port front first, then through the gasket to hold it in place, then align and push the bolts through the container.
• Optional: if you drilled holes for vents, push the covers in. They will fit snugly and should not require glue.
• Your container should now look something like this:
  
  
• Attach the feeder port back end by snapping it into place. Your final result should look something like this (this example is using back-end design B):
  
  
• Fill with feed, slap the lid back on, and you're done!

​

Project 6: Extension Cord Thru Hardware Cloth Adaptor​

This design came about after I had a persistent need to seasonally get a cord through hardware cloth to run heated bases for my chickens’ waterers. Plugs are big, cords are small, and stray HWC ends are sharp. After wood designs proved hard to swap for the seasons, and existing plastic ports didn't attach terribly well to the HWC, I decided to design my own solution. This adapter both fully protects the cord from hardware cloth snags once it’s installed, and it can have a cord installed/removed purely from a single side of the enclosure – no need for unbolting. There is also a little diamond-shaped hole in one part of the screw insert to "lock" it with a long, thin zip tie or piece of wire to stop the insert from being unscrewed. Since this will be a plastic insert into an otherwise wood/metal structure, I recommend mounting it a few feet up so that it doesn't become an appealing chewing point for rodents that may be looking for an entry point.

Print difficulty: fast but moderate difficulty with PLA. Difficult with other materials like PETG due to significant overhangs and limited tolerances on parts fitting together.

Files: front_plate.stl, back_plate.stl, screw_insert_A, screw_insert_B.stl

Recommended materials: clear or solid color PLA or PETG.

Other required parts: 4x pairs of #6 or equivalent bolts 3/4in or longer (you may need to trim longer bolts – the example images use 1in long bolts).

Scalable: generally no, but very small changes (<5%) may be ok to work with other HWC sizes if necessary. The tolerances on this design are likely to have problems if scaled too much.

Recommended slicer settings:

• Print slowly to minimize distortion of the threading. Moderate to slow speeds should be used even if your 3D printer claims it’s designed for ultra-fast printing.
• Do NOT enable any settings like “make overhangs printable,” which potentially alters the shape of the parts. Any change to the exact shape of the parts is likely to stop the pieces from fitting together properly post-print.
• Do NOT enable supports even if your slicer complains about overhangs or floating cantilevers. Supports are likely to be difficult to remove and cause rough surfaces/edges that prevent parts from fitting together properly.

Assembly and usage:

• This design is specifically for 1/2in hardware cloth. If you have a different mesh size, you may need to slightly resize the model to make it fit well. The bolt holes are designed to fit very close to the corners of some of the squares so that the unit can’t slip around.
• Use the flat, front plate part to find a suitable placement on the hardware cloth.
• Test that the bolts will go through smoothly and straight through all four holes of the front plate. DO NOT CUT THE MESH UNLESS ALL FOUR BOLT HOLES ARE COMPLETELY UNOBSTRUCTED! If you don’t have a place on the mesh where it fits, try printing the part at a very slightly larger size (this will require that all the other parts be scaled accordingly).
• Use a sharpie or similar marker, mark the inside of the large round hole on the hardware cloth.
• Remove the back plate.
• Using small snips to cut one wire at a time, cut just to the outside of the mark you made. Err on the side of possibly leaving too much and needing to trim later. The diagram below shows what your cutout should look like. Make sure to leave full squares of HWC intact as shown below (in-tact corners are marked in green):
  
  
• Try fitting the back plate through the hole. If it won’t fit, bend or trim the wires as needed, but make sure the bolts are going through complete, uncut squares (green in the diagram above).
• Once the front plate fits through, place the back plate over it on the other side and bolt into place. Don’t over-tighten or you may crack the plastic. It’s better to do this by hand and may require a helper.
• Place the power cord plug through the circular hole. Bring the halves of the screw insert together around the cord and screw into the front plate.

Software for 3D-Modeling

There is a lot you can do with 3D printers just using the ever-growing collection of 3D models available in various places on the web. However, 3D printers become an even more powerful tool when you start designing your own things. The first step in designing your own 3D-printable models is learning a 3D-modeling tool.

There are two general categories of programs for producing 3D-printable models: digital sculpting and computer-aided-design (CAD). Sculpting tools include programs like Blender and Nomad Sculpt. They are ideal for producing models for appearance purposes, like characters for video games and printable figurines. A sculpting tool like Blender can also produce functional parts; in fact, all of the projects in this article were created with Blender since that is the software the author is most familiar with. However, there are certain things that more sculpting-based tools do quite poorly even though they can technically "do" the tasks. For example, setting tolerances that can be scaled correctly with multiple objects. More traditional CAD tools include AutoCAD, Fusion 360, Sketchup, and FreeCAD.

I wish I could say there was one or more of these tools that was extremely easy to pick up, but, unfortunately, that isn’t the case. If you have no prior 3D-modeling experience with any similar programs, it is a decently large learning curve to get into any of the tools listed in the previous paragraph. It is also not entirely easy to move from a sculpting tool to a CAD tool and visa versa; there will still be a learning curve. Fortunately, you don't necessarily need to sign up for a class to get started with a new tool - there are many video tutorials available on the web for commonly used sculpting and CAD tools.

Once you have designed a model, whether in a sculpting or CAD tool, you will want to export it in .stl format. Then, you can import it into your slicer. Sometimes this goes smoothly and you are ready to print! However, it's also possible that the slicer can find problems with the stl file. Some tools are prone to this; Blender is one of them if you perform a lot of mirroring or shape-inverting operations when designing your model. One of the more common issues from Blender in particular is the presence of faces where the normals are incorrect (normals being what define the notion of inside vs outside for a model). These kinds of issues can cause the slicer to misinterpret how it needs to print walls and infill, and so they will need to be corrected in your 3D-modeling software and the file re-exported before it can print correctly. If you see areas printing fully hollow that should contain infill, you very likely have an issue with normals to sort out in your stl file.

Design Considerations for Chicken Safety

When designing 3D-printable objects for use for and around chickens, one consideration should be first and foremost: chicken safety!

Smoothness / Rough Edges

Although FDM printers work by extruding a continuous, smooth line of filament, they are still capable of making strangely sharp edges and corners sometimes. Prints can also have imperfections that can snag combs and wattles. This is especially true of anything where a chicken needs to reach into a container, like with a port feeder. If a chicken needs to put its head into a design, make sure there is plenty of clearance for its comb and that wattles can safely drape over the leading lower edge.

The smoothness requirement means that safe designs are likely to require two levels of bevel/chamfer on edges that are exposed to chickens: one level to get a general rounding of any hard corners and another over all edges to create a very small rounding effect. Edges that a chicken has no way to contact don’t matter for this, but be absolutely sure the chicken can’t contact them. Simply being at the back of the design against the HWC is not a sufficient safeguard; a chicken may try to force its face back there if the object can wiggle at all.

Below is an example of increasing levels of smoothness in a design: no bevel, a coarse bevel on the vertical edges, and a finer bevel on all edges. The rightmost design is the best one for chickens.


Even smooth designs can end up with some odd bumps and sharp bits from stray filament left as the print head moves between different parts of the model. Once printed, run you hand along all of the outer edges. If you feel any snagging of your skin at all, that’s an area that needs some attention from something like a deburring tool, hobby knife, or file/sander.

Supports (Best Avoided when Possible)

Supports are extra 3D printed material to help with overhanging structures in a print, and they are intended to be removed post-print. This removal process often isn’t entirely clean. Parts of the support nearest the model may be left intact and require filing to remove, or worse a support can be too well-attached and end up tearing a hole in the model on removal. Supports can also be extremely difficult to remove if they occur on the interior of a model with a cavity where they are hard to reach. Because of these potential drawbacks, support-free designs are always preferable when possible.

My method for creating support-free designs is to first sketch out a minimalist version of what I have in mind, then figure out what face still need to sit on the build plate to maximize how much else of the model is self-supporting while trying to visualize the way the filament will be laid down in each layer. I then look for overhangs that would be problematic (more on this in the next section), and try to rework each problematic area of the design.

Don't Rely on Glue for Multi-Part Designs

This is a design principle I had to learn the hard way when I first started designing. Unfortunately, food-safe glues and PLA/PETG don't mix very well...literally. No actual welding takes place between the surfaces with cyanoacrylate-based glues (CA or superglue) which are the most readily available glues that are safe once cured. This means that very large and rough surfaces can sometimes stick well enough, but it is likely to fail on thinner joins. Those glues that do weld the materials are both potentially hard to get and not food-safe. Alternatives to glue include:

• Friction-fit designs. Layer lines can work to your advantage for push-fit joints held in place by friction.
• Snap-fit designs where thinner areas of material can flex just enough to let the parts slide together.
• Bolts to hold surfaces together.

Tolerances, or how much gap you need to leave to account for filament thickness and margin of print error, are a significant part of designing friction-fit and snap-fit features. There are tolerance tests freely available on the web that you can download and try on your printer to determine what kinds of gaps you need to allow in designs to accomplish friction-fit and snap-fit.

Below is an example of a push-fit design where parts are held in place by friction. A small gap allows the halves of a dovetail joint insert to be squeezed downwards into a hole. Once in place, the layer lines on the parts create a lot of friction and make the parts very difficult to disassemble.


Center of Gravity, Stability, and Strength

Chickens jump on things. To some extent the need for a tip-proof design depends on the nature of the chickens its around. I have some fully 3D printed feeders that are just fine in with birds that are well-behaved around them. If I were to move those same feeders to another flock, they would be tipped within minutes and likely eventually smashed to bits from abuse. One way that you can avoid tipping is to hang the object or otherwise anchor it to a wall. If hanging from hardware cloth, use multiple loops to distribute which wires are taking the force and to stop the object from rotating.

3D-Printed objects also need to take punishment chicken beaks. While chickens may not be very strong, what force they can apply gets focused on a very small point at the end of their beak. Don't make your walls paper-thin! Although strength can be controlled to a degree within the slicer settings (add more wall layers, denser infill, etc.), if your walls are too thin then those settings will have limited effect. For larger designs, err on the side of thicker walls to allow those extra slicer settings for strength to actually have an effect.

Holes and Overhangs

Holes in feeders in particular need some care. If it's big enough for a chicken to even think about shoving its head in, it needs to be big enough for the chicken to do that safely and have comb clearance. If it's not meant for a chicken head, don't make it big enough for a chicken to get more than the end of its beak inside. My personal experience has been that hens are more keen on shoving their heads into small spaces than rooster are. Because of this, I strongly recommend against feeder designs that try to limit how much of a hen's head can come in contact with the feed. If the feed level gets low and the hens are hungry, they will try to shove more of their face in than fits safely and will damage the front of their nares or comb, or even potentially damage their beaks.

With a few exceptions, most consumer-grade FDM printers can only print very small overhangs reliably. This means that a large, horizontal surface hanging in the air is likely to fail due to sagging filament. There are test designs available on the web that you can print to determine what kinds of overhangs your printer can handle. One reason to be careful with overhangs even if your print doesn't completely fail on them is that sagging, poorly adhered strands of filament are a dirt trap and will be very hard to clean without damaging the model. This is obviously something to avoid for a model intended to hold feed.

Overhangs at roughly 45-degree angles out from horizontal are usually printable without issue. Some printers can manage significantly lower angles. However, the closer you get to a pure vertical wall (90 degrees from the build plate), the more universally safe that wall is.

Circular holes through vertical walls and arches may seem like they should print just fine – and they usually do when small. Larger holes and arches may struggle. For holes, the bottom half should always be fine; it's the top curve that is problematic. Failure in mild cases will show drooping bits of filament along the underside of the arch, but the print may otherwise be fine. Larger arches can cause a more serious print failure if the initial bridge across the middle of the top collapses, leaving nothing for the next layer to adhere to. One way around this problem is to make holes diamond shaped, with points at the top and bottom.

Below is an example of a gravity-based, fully-3D-printed feeder design of mine that, although not ready for public usage, demonstrates substitution of 45-degree angles for the more traditional, unsupported, horizontal overhangs that are used in this type of port-like feeder. Feed is intended to flow in through the back into a chicken-accessible space; it can do this through a rectangular hole as is the norm, but it can also to the same thing through a 45-degree triangular hole! Although it looks strange, that aspect of the design actually works quite well (what doesn't work as well is the lack of anchoring points for stability as per the section above on center of gravity).


Prototype, Prototype, Prototype

Never assume that your first print of a new design will be ready for immediate use out with your flock. For large designs that will consume a lot of filament, you can minimize prototyping waste for testing mechanisms that you’re not confident in by printing just the mechanisms in question by themselves (like just printing a hinge by itself) or by printing at smaller scales.

Once you know your design will print and any snap-fit, hinge, etc. mechanisms will work as intended, test your design with your chickens in a supervised setting. If you have curious but calm chickens, those should be your beta testers. You should always try to anticipate as much of their interactions as possible (trying to jump on things, sticking their head in holes, etc.), but they may still find problems or interesting new ways of interacting with your design that require going back to the drawing board to make it more compatible with your flock.

Example of one of my more gregarious roosters helping me test the comb clearance of a design: