Here are the first stages of my 20 gallon waste free feeder. Using four 4 inch 90 degree elbows. Say that 10 times fast.
Drilled half inch hole with drill bit, then used jig saw to widen holes to 4 inches.
As you can see, the holes were not perfectly round! Haha. But that is ok. All the tubes took a little bit of squeezing to get in, so nothing is super loose. Just larger versus smaller gaps in certain spots.
Gaps are not an issue because.....drum roll...I used expanding foam insulation instead of the classically recommended caulk or silicone. Check out this beauty. Haha.

The random stuff in there is to hold the tubes in the correct position off the floor of the tub until the foam hardens. As anyone knows who uses the cans of foam, you can't really save any leftovers unless you want to use some solvents to clean out the tube before it sets up. So I just used all the extra from the can to link all the tubes together within the tub. I figure this will give it some stability inside and not allow any of the tubes to move much due to being linked to the one next to it. Since it is all inside the tub, I am not worried about it degrading due to UV exposure or anything.
After it is all cured overnight, I will trim or sand down all the foam on the outside so that it is flush with the tub. Or at least flat and less attractive for pecking. Will the chickens peck at it? Maybe? Time will tell. Maybe I will end up coating the foam with a layer of tape or something that the chickens don't have an interest in pecking. It is paintable. We will see.
Also pondering creating a false wall inside the tub so that there is not feed sitting and getting old/stale on the "far" side where there are no feeding tubes. Feels like it would be a waste of the tub shape, but I plan to have this feeder along a wall, so it does not make sense to have feeder tubes all the way around the tub.
More photos to come tomorrow when I trim it and make it pretty. Then probably a 12 week wait until the chickens are big enough to even use this thing! Haha!