Here are some pics of a pickup bed trailer with a camper shell that I made into a brooder pen. The trailer didn't follow well and was just sitting around the yard so I made use of it. The windows slide open and have chicken wire over them for ventilation and I attached the feeder to the ceiling of it. I just moved my chicks out of it and will now be using it as a quarantine pen for a bit for a rooster that is coming to stay with us for a while. I like that it is mobile. I had it at the other end of my pasture this summer and out of the way, but for the winter I brought it up close so I don't have to shovel all the way out to it.