I’ve made 2 of these, they’re great. I also have a few that are just plastic tubs with pvc elbows going into them, and I shorten the length of the side that goes down inside.
I took a hole saw to a rubbermaid container. Sort of like what the guy in the video below makes, but I didn't bother with the extension he puts on top. I need a solid top to be sure the food stays dry. My setup will get some rain in it from time to time. 2 containers, around 30 birds. They go through about 1 full one per day.
I'm going to dabble in making these and looking into shipping options. I need more, and they don't seem to be available any longer. Time to put that really nice shop to use.