I haven't. I was under the impression that guineas didn't use them. Reconsidering that impression, but if I put them in, I think I would get plastic milk crates bc they like to be able to see while feeling hidden, and they'd go under the drop boards.
On etsy, someone has made frames for 5 gal buckets - it holds the bucket stable on it's side
, and has a front 3-4" rise to keep material inside. Depending on your breed, you may not need even a 5 gal.