We have a small coop - 4 chickens currently coexisting. We use freestanding nesting boxes and originally used a kitty litter box. When we redesigned the interior of the coop (to put in a roosting ladder) we found that the kitty litter box had to go. Our substitute was 2 wooden wine boxes that we got for free from our local wine store. They're the perfect size for the hens and we had no trouble getting them to switch.