I guess I could go the expensive way and buy house windows, but they need to be modified for hardware cloth and what not anyway so I was thinking, how many design your own? Something as simple as a sheet of plexi in a frame than can be opened would work fine, right? This would be a one pane window that would lift up much like a typical home window. Because looks will not matter inside the coop it would be fine to have the window open all the way and just on the outside of the wall. Imangine a frame that the window can run in on the inside of the coop, but this frame channel runs twice as high as the window above it. Add in a couple spots for a pin to lock the window in place and it's adjustable and lockable. Thoughts???