Here are pictures of my own coop along with design tips. I repurposed an old wooden bar to create mine. The rule of them is 2 square feet of interior space per chicken and 2 square feet of exterior space. I doubled mine just to be safe and went with 8 square feet of interior space for 4 chickens and 16 square feet of exterior space. They also now have access to an entire side of my yard which I now treat as my composting area.