I've looked into those. But the price is quite high, whilst a big bucket is cheaper.
Yes, that can definitely be a problem.
All of the DIY feeders involve another large bucket bin, and pipe. Is there a way to do it without pipe?
I think you do need the pipe, or something else that works the same way.
If you just put feed in the bucket and leave the top open, the chickens eat from the top, throw out feed, poop in it, and cannot reach the feed when the bucket starts to get empty (unless they sit in the bucket.) Of course that's why people came up with better methods
If you make holes near the bottom and do not use the pipe, the feed falls out through the holes.
The pipe makes it so the chickens can stick their heads in to reach the feed, but the feed cannot come out the holes. I think it does have to be something sturdy, and the right size and shape, to work right. PVC pipe is available to many people, not too expensive, and comes in the right dimensions-- which is why it's so popular.
You might be able to cut pieces out of some kind of plastic container, but it does need to be sturdy enough that the feed in the bucket will not crush it, and of course you need to be able to attach it to the bucket somehow. I suggest you look at every plastic thing that will get thrown away in your house, and see if you find ones that could work. Maybe a round jar? (If you turn it on its side, attach the mouth of the jar to the side of the bucket, and cut out the bottom side to let the chickens reach down into the food.)
I'll be watching to see if anyone else suggests an alternative to the pipe, because I'm curious too.