Here's one:
I didn't use all the hardware as I've had a hen with hardware disease in the past. I bought large wooden beads and screwed them directly to the bolt, no washers or nuts to swallow.
I've made and used those. It took the polish girls a little time to get used to sticking their head dresses in the holes. Mine weren't gravity fed as I didn't want them to be stationary. After almost a year of going out to put the feed away at night (didn't want to attract unwanted pests) and...