The pen is 4'x10'x3' tall, wrapped with 1/2" hardware cloth. The top lifts up (3 piano hinges), chicken wire covered that wavy fiberglass stuff. It has a plywood sleeve around one end that breaks the wind (that's where the perch is), and the nest box hangs on metal straps inside the other end. My brother put wheels on one end, but they don't work very well due to the weight. Since I don't move it much, I keep it about 6-8" deep in oat straw. I toss a handful of sunflower chips over the straw, and they fluff up the straw looking for the seeds. If it isn't raining or snowing, I usually let them run loose most of the day. They go back inside by themselves close to dusk, and I just close the small door and pin it closed.

The light one will be 4x8x2' tall, made from just 2x2s and chicken wire, with just an 18x18" door in the top of one corner for putting them in. To let them out, all I have to do is lift the pen.

When it rains, they come up on the deck and line up, staring in the glass door. Four hens looking in, four cats staring out.