Here are the hand-drawn plans that my younger son and I came up with.
33806_floorplan.jpg
33806_north_wall.jpg


33806_south_inside_wall.jpg
33806_west_wall.jpg


33806_east_wall.jpg
33806_west_inside_wall.jpg


These are the original (first draft of our plans. I am hoping to be able to redo these drawings with the correct measurements we used and get them posted as soon as possible.
My husband and I followed these as closely as we could, not being professional carpenters, and our end result is wonderful, predator safe and efficient.