We built our new coop this fall. The girls were still young and I got busy with work so I never finished the nesting boxes. I've left a space which is currently covered over with wood for the nesting boxes to go. I've decided on external boxes since my coop is pretty small (4x6) and while I only have 6 birds now, I just know that I'll be wanting more and will need the space. I'm quite sure I have the design down but I'd really like to insulate them. I'm thinking of using that insulating foam on the inside of the box but will obviously need to cover it so the chickens won't peck at it. What would you recommend to cover it? I'm already a little tight for space so I want to use something as thin as I can get away with. Should I use a thin layer of plywood or perhaps linoleum? I'm just wondering what my options are. Any ideas?