This is my instructions. You can build the same using any materials available.
I thought about my design and I thought I'd add the following info for those who are going to build it, more like how I'd suggest starting.
First, I'd order the parts from the parts lists. The parts from Dealextreme.com take 3-6 weeks to arrive, so I'd order them first. Then, order the platinum RTD. Note, the Chinese RTDs are horrible, don't buy them. The controllers aren't bad, but buy american made RTD. That listing for Ebay may or may not be good, but the company is always selling on ebay. They seem to have a great product for the price.
Ok, so you have the controls ordered, now go find some hot rollers or curlers. It's the kind with the aluminum "fingers" sticking up off an aluminum base. I think I included a link. Anyhow, I bought mine at a yard sale for less than $5.
Ok, so you have parts on the way, now go buy a little giant egg turner and unpack it from the box. (Bargan foods on hwy 8 has em for less than $40.) Anyhow, use something to build a tray to set it in. I used the plastic angle that is used in shipping pallets of boxes. They put plastic angle on the corners and then shrink wrap it. The plastic angle is usually thrown away. I used it to make a tray by cutting it into 4 pieces of equal length and fastening them together with small screws so that you have a tray that comfortably holds the egg turner. You do NOT need anything solid under the egg turner. You can put hardware cloth under the eggs if you so desire, but you don't need anything. Make sure your tray or "rack" is wide enough to hold the egg turner and not interfere with the moving parts. (You may wanna plug it in and make sure it can cycle the eggs back and forth without getting stuck. Takes hours to complete a cycle.
Now, use the tray as a guide for the INSIDE dimensions of your incubator. This is JUST the main compartment and Remember, it is the INSIDE of the incubator. Leave at least 1/2 inch all the way around the rack. It doesn't have to fit snug on each side or the front and back. Note, I say the main compartment, but in truth you need room behind the false wall to mount the fan and heating assembly. So, if the outside of the rack is 16 inches by 16 inches, then you would want to make the INSIDE of the incubator 16 1/2 wide by 20 - 26 inches long, depending on what you think you need. Maybe even more. If you go ahead and get the metal downspout material and a metal 90 degree, that should help you decide. You'll need a little extra space on the back for the fan which is probably bigger than the downspout. Now that you can lay out the bottom of the incubator and start thinking about how close you can mount your racks together and how many you may want for expansion and therefore how tall you want to build the incubator. Remember, you will need space for jars of water on the bottom for humidity control (we place ours in the back corner of the main compartment). You may want to add a light to the top of the incubator so leave space for that. I used a 110V LED under cabinet light. You do NOT want anything that will give off significant amount of heat for obvious reasons.
Once you decide on how tall, then cut your four corners out of 2X2 (I ripped spruce 2X4's into 2X2's). mount the corners to the bottom and then copy the bottom to the top. You should have a rough frame when you have that assembled. Oh and I suggest using wood screws. Next, decide on where your false wall will go and add a vertical piece of 2X2 to the frame on each side where the false wall will be located. (So you have something to fasten it to later). Next, install the inside of the incubator. I used white plastic material, but it's hard to find. You can probably use thin plywood and paint it with a good latex paint. It will take a few days to cure out well before you can use it without fumes. I figure fumes will kill the eggs, but I could be wrong. This is why I went with plastic. Once you have your inside top, bottom, and two sides installed, then install the false wall. You may need to use some sort of bracket or you can cut a few pieces of 2X2 to mount to the false wall and to the inside of the main incubator wall. In any case, leave a gap at the top, probably 1-2 inches? Now, you can start adding more angle pieces to each side of the main compartment to hold your racks. Construct a door using 2X2s and set it on hinges. Install the heating element assembly and run the wires out to the top. I put an insulated piece of plywood on the back (two pieces of insulation and then plywood on top screwed to the back of the incubator. Honestly, I wish I had framed a second door and mounted the door on with hinges for easy access to the heating element.
Drill some holes along the top above the false wall and just behind the false wall for the RTD and the digital pharmacy thermometer. Insulate the top, bottom, sides, door, and back with foam board insulation. Drill holes in the top and bottom for ventilation. How much do you need? I have no clue! I use 3 aquarium aerators for mine. :-) I do not suggest that. It's better to drill holes and add more till you have successful hatches and then add a few more for expansion.
I put a window in the door, that's up to you. The rest is simply wiring up the controls and testing everything. Always make sure the fan stays on all the time. The heating element should only come on when signal comes from the controller, but the fan must be running all the time. I put a switch on the outside for my light as well.
Ok, I spent a LOT of time in research and I finally built my own incubator. We get GREAT hatch rates now. I believe the number one thing is to get the temperature right before you put eggs into the incubator. Then, the temperature has to be stable. To calibrate the temperature of an incubator, we use a digital pharmacy thermometer. They are the only thermometers you can buy that are FACTORY CALIBRATED! Buy one, check it on yourself, if it is right, then use it to set the incubator. Now, the little giant, even with a fan is not very stable at all. It is very bad about drifting every time the room temperature goes up or down. The wafer thermostat is a very poor controller for incubation. It cycles on and off many times a day in an attempt to maintain temperature. If it sticks ON at any time, even for a few minutes, then it can cook the eggs and destroy any chance you had of a hatch. I had one that went bad half way through a batch and we caught it cause we had a cooking thermometer with a high-temp set to sound an alarm at just 2 degrees above 99.5. I moved the eggs to my home-built incubator and removed the old thermostat from the LG. The LG is now used as a hatcher with a digital temperature controller that I purchased along with a solid-state relay and a platinum RTD. The controls assembly is probably $50, but now it doesn't matter what the temperature in the house does, the controller maintains 99.5 plus or minus 0.1 degrees. The solid state relay will never "stick" in the on position. If it fails, it will fail in the OFF position due to the design. The same controller setup controls the temperature in my home-built incubator. I used little giant egg turners that set on trays that slide in the front. Air is sucked out of the incubator at the top, through a heater in the back, blown back into the incubator at the bottom. All the guts are hidden inside the incubator cabinet. I have hatched eggs for a while now, and to be honest, they appear to be pretty forgiving on humidity. We have successfully hatched eggs that were incubated from 30 to 45% humidity. That's a pretty big window. However, I believe temperature is the most critical factor. Get a digital pharmacy thermometer, rather, get TWO of them. Stick them into the incubator so the fan will blow on them away from the heating element. Test your temp every day, twice a day. Get it right and then add the eggs. Confirm it it is right every day. That is how I get great hatches.
Anyone who assembles the electrical should be knowledgeable in electrical code and should understand that I am NOT responsible for any injury or any damage that can come from incorrect installation of the electrical parts. I am not responsible in any way for what you do with this information.
Ok, basic physical design is this. The LG turners are approximately 15" by 15" if memory serves me. So, I built the main compartment to be 16" by 16" on the INSIDE of the incubator. Now, the incubator is actually much deeper than just 16 inches to make room for the heater and fan that is in the back. It has a "false wall" 16 inches back from the front. Behind the false wall is the heating element and fan. The fan is a 120 volt 8 inch fan, looks like a computer fan, but bigger. It is mounted to standard metal downspout. The downspout houses the heating element which is just the aluminum guts out of an old set of 80's curlers. Believe it or not, it is the absolute best heater for incubation. After the heating element, the downspout goes into a standard downspout 90 which sticks through the false wall to return the heated air to the bottom of the incubator. Air flows up around all the little giant egg turners and is sucked out at the top of the false wall. The false wall has a 1 inch gap at the top for air flow. The platinum 100 RTD (PT-100) sticks through the top of the incubator right at the top of the false wall. This is the most efficient place to measure temperature. Beside it is a digital thermometer. The incubator is framed with 2X2" spruce. It is lined with plastic panels for easy cleaning. It is insulated with foamboard and covered with thin plywood or paneling. It has plastic angle pieces to support the shelves (blue). The door has a double-pane plexiglass window and I have a dimmable LED light fixture in the top that can be turned on from outside. I built trays using the plastic angle to sit the LG turners in.
The solid state relay does not fail closed like a mechanical relay or a thermostat (like is used on cheaper incubators). They are intended to last a VERY long time. Orders of magnitude more cycles than a mechanical relay or mechanical thermostat. That means RELIABLE! If it fails, it fails open, which means it just stops sending power to the heater. The incubator goes cold. Replaceing it would bring the bater back up. If you do it fast enough it would probably still get successful hatch. (Eggs can go cold for up to 24 hours and still have a reasonably successful hatch.)
Now, the fan I used is bigger than that one, I think this is a 6 inch. Don't use a cheapy dollar store brand fan. This fan has to run continuously for months maybe years at a time. So, get a industrial type fan. I bought mine at a flea market. Barely used. Like $3. The curlers were purchased at a flea market for $2. I disassembled them down to just an aluminum plate with the "fingers" sticking up and the heating element and wire sticking out. You will need a box that meets code to mount the controller and solid state relay in along with the fuses. The curlers will slide up into standard downspout (the stuff that's used on the side of your house to route the water from the gutters). The metal downspout will safely house the curler guts. Mount the fan on the top blowing down into the downspout with the curler guts (heating element) below it. Then put a downspout 90 on the bottom using a self tapping metal screw. ELECTRICAL HOOK UP: Mount the fuse in the side of the box so you can change it from the outside. Use a standard 3-prong wall outlet "pigtail". Run the pigtail into the box and ground the box. Hot goes to one side of the fuse. Other side of the fuse goes to the AC side of the solid state relay and to the digital controller LINE AC terminal. Hot goes from the "load" side of the solid state relay out to the heating element. Neutral goes to the heating element and to the controller. Now, RTD. RTD wires can be trimmed to correct length and then stripped. Connect RTD to the RTD input on the controller. Don't worry about which of the three wires goes where. Hook it up and then power it up. chances are, you are wrong and it will say "EEE" for error. change TWO wires and try again until you get it working. Note the fan should be wired to a pigtail and plugged in at all times when the incubator is running. Now, use the manual to set the controller to degrees F. Set it to 99.5 and let it come to up to temp. Use the digital thermometer to see how far off it is. It WILL BE OFF AND WILL REQUIRE CALIBRATION! Subtract the measured value from the controller from the value of the thermometer. Use the controllers manual to "calibrate" the controller. Allow it to come to temp and settle out again and check the temps. Continue until you get it to 99.5. Run it a day or so to ensure everything is stable. Add egg turners and a jar or two for humidity and you are ready to go. Note, you MUST ventilate your incubator. Fresh air exchange is a must for eggs to develop. I am running three fish tank air pumps along with some vent holes. Seems to be the right amount of air for me. This is where experience counts. You have to figure out what you need. More eggs, you'll need more fresh air. IF you have a means to measure Oxygen content, you can add more vent holes or cover some to get it right. Otherwise it's a test and see, which is what I've done.
The carpentry and then finding a suitable heating element took the longest. Most devices that heat either give off way too much heat or they "stink" when they get hot. Believe me, I tried most everything I could get my hands on. The curlers simply worked. Test the ones you get to make sure they don't develop a smell when plugged in for a few minutes. Also, when you build the incubator, be very careful about wood selection. I origionally built my shelves out of spruce. They were beautiful! But, then I couldn't use them, they gave off a resin smell. I was afraid it would mess up my hatches. The plastic angle material that I used is actually corner supports for shipping boxes on pallets. They put these on each corner and then wrap em with shrink wrap. They are pretty common and are usually thrown away after one use. Make great shelves and they work well for the trays as you can see. Oh and one final comment about this project. As best as I can tell, most of the 80s type curlers are 300 watt. While it works great as a heat source, it's actually a bit more than what you need. The controller will turn on and off to regulate the temp, but it works a little better if you make a simple adjustment. I installed a diode inline on the output from the Solid State Relay. The diode in essence drops the heater from 300 watts to 150 watts, which is much closer to what you need. (Diode should be wired in series on the hot wire leaving the solid state relay.) Get a couple heavy duty diodes. I actually put two in parallel and then put that in series so that I'd have a "backup" already there. Once everything is up and running, you will need to calibrate the controller and then Tune the controller. If you use the same controller as I have and you install the diode, then I can simply give you my tuning parameters and that should get you very close. ALSO, I installed a basic lamp dimmer switch inline between the solid state relay and the heating element. It helps to dial it back some. Some solid state relays will not like it if you dial it back too much. Just tinker with it and you will see. Now, the best part of building this yourself is that you can maintain and repair anything that could ever go wrong. You aren't scared to adjust something or tweak something as you think it should be. The forced draft design keeps all the eggs at the same temperature. If you wanted too, you could add additional fans on the sides of the exit at the bottom. I don't think they are needed. Now, we do NOT hatch eggs in our incubator. I'm very anal about keeping my incubator clean. So, we always move eggs to the hatcher as soon as they pip. This way the incubator stays clean and I don't get all that feather dust in my heating element and fan assembly. Now, when you place your order for parts from deal extreme, I suggest ordering two of everything. You can build a controller for a hatcher and if anything ever went wrong, you can then swipe parts and get the incubator going again quickly. Remember this, the solid state relay, if/when it fails, it always fails open. This means it fails in the "OFF" state so that no power is being sent to the element. The only way you could have serious over-heating is a failure of the controller or the RTD. American made Platinum RTDs have a very long service life, probably 20 years and I have had no problems with the controller. You can purchase much more expensive controllers if you desire, but I found this does the trick. Let me know if you need any help. If I was smart, I'd charge a fee for installing the electrical components and wireing them up. I'm not the best carpenter, but I can install, wire, and program the controls!
Now, I've been running mine for probably 7 or 8 months without any trouble at all.
The incubator INSIDE dimensions are 16 1/2 inches wide and 24 inches long. The false wall is 18 inches from the inside of the front door. That should be enough for anyone to build a basic cabinet. I used 2X4's that I ripped down to 2X2's for the frame. I put plastic material on the insides and then insulated with foam board. Covered the foamboard with paneling. Now, you can choose to build yours out of simple plywood, or you could repurpose an existing cabinet. It's all up to you. On the top, I drilled several holes just above and slightly behind the false wall. These holes are for the digital pharmacy thermometer, RTD, and cooking thermometers that have a high-temp alarm. My design is 28 inches high on the inside. It will easily accomodate 5 LG egg turners on racks. If I move them closer, I could probably fit 6, maybe 7 into that space. Note, these are INSIDE dimensions. You can go taller if you like, it should work fine and would hold more LG turners. The little giant egg turners are 15 inches by 15 inches. So, get a spare and build a frame or rack that will support the legs of each turner. You can put wire in the frame under the egg turner or leave it open, up to you. The frame MUST be able to slide into the completed incubator and must not interfere with the motor and leavers that turn the eggs. I used the same plastic angle to make "shelves" on the sides of the incubator for the racks to slide into. I plan on incubating duck eggs, so I left some extra space between mine. It's good cause I can reach my hand in to candle eggs without pulling out the rack, but if I need to add more eggs, I'll move all the shelves closer together. I found a LED light fixture intended for under cabinets and installed it into the top. Wired it to a standard 120V light switch mounted to the top. Now, when I started mine up, it smelled strong like freshly cut wood. I assume it was the rosin out of the spruce that I framed it in. The racks smelled really strong like rosen, so I wouldn't use them. I put activated carbon in it and increased airflow and just let it run for a couple weeks till the smell died down. It may have been fine, but I didn't want to add eggs until I was sure. The wood racks smell fine now and I could probably use them with no problem. I think the piece I made them out of had a very large amount of sap in it. Lining for the incubator? You could probably use shower stall panels? I was able to use plastic panels I bought locally from a guy that resells odds and ends. Wood will probably be fine, especially if you paint it and give it some time on temp to clear out all the smells. Ventilation. Simple as this, eggs won't hatch if they can't breath. Eggs actually breathe quite a bit through the shell. So, if you don't provide enough ventilation, you will get a buildup of CO2 and your eggs will die off until there are very few left (if any). So, you MUST drill holes in the top and bottom for ventilation. How big depends on the number of eggs you have in the incubator. Maintaining temp is easy with the 150-300 watt heater. The only variable left is humidity. We keep our incubator in our home, so the AC and heat dries the air out. Julie uses either 1 or 2 clean cherry jars for the humidity source. It varies based on season and how much the AC or heat is running. Now, I simply put a back on mine using wood screws. It is built the same as the sides. If I had it to do over again, I would install the back with hinges and latches so I could open it up easily. I'd put my water jars in the back. Now, for anyone concerned about the electrical, the controller comes with a pretty detailed wiring diagram that is pretty simple. Anyone who knows a reasonable amount about basic household wiring should be fine with it. As I mentioned before, once it is complete, you need to calibrate the temperature on the controller, (it may be off by up to 3 degrees F prior to calibration). This is why the digital pharmacy thermometer is so important -for EVERY incubator. You need a factory calibrated thermometer to CHECK and adjust the incubator as needed. Once the controller is calibrated, it should remain so for quite some time, however, it is wise to hit the little button on the pharmacy thermometer every day and check the temp. Only takes a second since we leave ours in the incubator all the time. If it ever reads "off", I swap it out for our secondary and get a "second opinion" before changing the calibration on the controller (Very Rare). Any time you open the incubator, the controller "winds up". This is normal. When you close the door, the incubator will heat up and overshoot the 99.5 that you have set. Again, that's normal. As long as the overshoot isn't too much (ours will go to around 102F) and doesn't last long, the eggs will be fine. Julie opens ours at least once a day and checks eggs. The bator overshoots every time and it doesn't cause any issues with hatching. One last detail is the LG turners. I decided to use them because as I need more space, I can just purchase another. They are pretty reliable and are easy to get. I figure I'd take more time and money designing a turner than just using something that is already tried and true. Failure on one turner does not ruin all the eggs. (All eggs in one basket principle). Chances are, most people with chickens already have one anyhow. To power the LG turners, I simply cut a kitchen type extension cord that will take three plugs. I ran it through a hole in the top, front corner of the incubator. I used lugs to put the wire back together and plug it into a power strip that is mounted to the top of the incubator. Everything plugs into the strip. Continuous power consumption: once the bator comes up to temp, the controller only "flashes" power to the heater every now and then. The fan probably uses more energy than the actual heating element once it's on temp. Well, there you go, a book on how I built my bator. That should be enough info for anyone who is handy to build one as good or better than my own. It does take some time, and once you get it going I suggest running it at least a couple weeks to clear out any rosin smell and to ensure it's reliable. The digital cooking thermometers are the kind that use a triple A battery and have an alarm for when it reaches a preset temp. They are horrible on accuracy because one claims the temp in the incubator is 108 degrees F while the other says 103! Now, it doesn't matter, cause all I do is use them as an over-temp alarm. I set the high temp alarm on it to be just a couple degrees over whatever it is reading at steady state. It may go off after I open and close the incubator for a few minutes while the controller overshoots the 99.5 setpoint. That is a good test. The alarm is cheap insurance. I recommend it on EVERY incubator. (It saved my first batch of eggs in my first little giant incubator, the contacts stuck closed and it overheated.) We just happened to be home at the time and was able to move the eggs out of the LG and into my homebuilt incubator that I was still testing. Talk about perfect timing! For anyone that is new, hatching eggs is one part having the right equipment and one part experience. It takes some experience to know what will work for you. For anyone starting out, and for anyone who is testing a new incubator, I recommend you buy some cheap eggs and practice a few runs before you get into expensive birds. Again, I take no responsibility for how the info listed here is used. I am not liable for any damage if anyone uses this info to build an incubator. I have had great success with it, but I cannot guarantee you will.
I mentioned the term "steady state". This is where the incubator has been closed and has achieved a steady temp for at least a few minutes. THIS is when you check the temperature and do calibrations. NEVER check the temperature just after opening the incubator. If the temperature is changing, you cannot rely on the digital pharmacy thermometer to read the same temp as the RTD. My door is made from a 2X2 wood rectangle frame with plastic panel on the inside. I framed out a window in the middle with 2X2's and then cut out the plywood I put on the outside. IN the middle of the plywood outside and plastic panel inside is foam board insulation. I then used two pieces of plexi-glass, one on the outside, another on the inside so I have two layers of plexi-glass for the window. The double pane window really helps to insulate the incubator. I also used weather stripping to seal around the door and window. Funny that I did that cause then I turned around and drilled holes for ventilation.