Like someone else suggested, you can just make your external square box like you would see on any coop (in the coop section) that has external boxes. On the INSIDE of your coop, that is where you'd place a board over the opening of your nests and just cut out a circle-- just like Gallo Del Cielo showed you on theirs. Easy! Then you can still open it up from outside just like you normally would on any other box and access it. The only difference is that the board covering up the entrance to the boxes have round holes cut out of them inside the coop instead of being exposed to show that they are square. To cut your holes in your piece of wood that will cover the boxes- you'll want to use a drill with a large hole accessory on the end of your drill-- like the attachment used to cutting pot lights in your ceiling and use that to get your hole started. (that's what I've been using and it works fine) Then use your jig saw to get into it and cut out the rest of the circle you drew on your board. It would be pretty easy to do.