Golf Ball Feeder
The ball stays in place with a cage made of u-bolts.
Inside view

Outside View

Bottom view

Complete View

I used 3 inch pcv pipe, 2 45% elbows, 1 end cap and 1 4inch to 3 inch adapter at the filling end. I don't recall what size the u-bolts are as I had them laying around.
The general idea is to allow the ball some up and down movement but not to get completely away from the hole. The outside view picture shows how much play there is. I use crumble, for pellets I suppose you would want to increase the play. The chickens peck at the ball and a small amount of food spills out for them to eat off the ground. I haven't seen rodents in my run since I made this thing.
I was worried at first that the girls wouldn't figure it out but as soon as one did a few hours later they all had it down. I'm thinking about modifying it to hold more feed as I get about 6 days and would like to get at least 7 days between it and the feeder I have inside the coop.
Inside feeder