Needed a coop and decided I liked the tractor concept. I have a small kubota to aid in the moves. Birds will be free range when someone is around. Most days Coop is 6' × 18' with stained plywood walls and a steel roof. Still have some stuff to finish. Each end is about 6x6 with 6' open in the center.it is going to hold 8 chickens in 1 side and 4 ducks in the other. I decided to bump out the nesting boxes and run that up to the roof to provide storage. Has been fun building it over the last couple weeks. Open area is covered with1/2 " hardware cloth. The occupants. ...at 18 days old.