My coop (under construction) is a little too tight to put nestboxes on the floor, so I am planning on hanging them on the outside after they are built ( The chicks are only 1.5 months.) The boxes will be made from plywood and permanently attached to the coop. It will have a hinged roof or back for egg access and cleanout. When I am ready to install them, I'll run a circular saw over the coop sheathing (a SHALLOW cut) to cut out a rectangle, install a 2x4 along the bottom edge of the new opening for support, and screw the boxes to the coop framing.