That's great. I think I will make one too. I have an old bathtub in my chicken yead. I saw
chickens get in it all the time, so I put some sand and diatomaceous earth in it thinking it makes a great dust bath. The chickens did not agree. They never use it. I haven't seen them in the bath since.
You could put a board, or branch in each corner and give it a little slanted roof. It would keep most of the rain out, and provide shade.
Thanks