I would like to use plastic storage containers as nest boxes, but am not sure how big they need to be. I haven't seen any 12x12 ones. I did find some 13 1/4" by 8 1/4" ones today, but wasn't sure if they would be wide enough. I just like the idea of being able to take the boxes out to clean them, or to move a broody hen if I need to. I'd appreciate any suggestions.