My pullets were getting too big for the little tool shed but I couldn't put them with the main flock yet because those dudes are vultures and they would have pecked every feather off their little heads. A friend of ours wanted his old camper hauled to the dump and VOILA! there was my new chicken coop.
I covered the overhead bunk opening with chicken wire and put my new fledgelings in there. Then I used chicken wire screens to covered the holes left in the counter where the stove, sink and fridge had been and I put my baby chicks in that area. They only need the brood light on at night. And the pullets have the main camper living space. They love their little roost along the window where the dinette used to be. Now all I have to do is grow some clematis or virginia creeper or beans over the camper to camouflage it, lol.
Old campers are easy to find. They cost money to dispose of them so people often give them away - check/or advertise for one on the online buy and sell sites.