I saw a picture of a trampoline frame that someone turned into a chicken pen and thought it was a cool idea. I put an ad on craigslist and got 3 free trampoline frames that day. I put one in the barn and set the other 3 up. I bought some 30" fencing for $25 at the home improvement store and went around the perimeter of both frames. I zip tied it on. It worked out great. Next I put chicken wire on the top of one to keep the birds out and keep the chickens in. The second one I will put some support in the middle because the chicken wire sags. Also, it is difficult to go in and get the birds, unless you are 30" tall. I am building a small chicken coop for #2. I will attach it to the side and rig the door so I can open/shut it from the outside. The lumber for the coop I bought at an auction. I paid $40 for 2 truckloads of lumber. The shingles I paid $1 for at a different auction. I got the old windows for free. When its all done, I will have less than $50 in the whole affair. I plan to keep 6 layers in it.