I used these last season as "grow out" pens to raise 42 Light Sussex chicks. After the chicks don't need heat and before they were old enough to be added to the flock. 7 to a brooder and raised to 4 months old. There are 15 sq. ft. per corral. Put a tarp down under the corral. Just any cheap one will do. Then go to tractor Supply and buy a bale of their hardwood chips. The ones in the white bale, not the yellow bale. Put in chips to about 3 inches deep. Cut a nice "V" notch in opposite sides of the corral and lay in them a strong piece of PVC or wood pole. Hang your feeder from that with a line or chain which can be raised as the chicks grow. The level of the feed they peck at should stay at shoulder level. Put a raised platform in the corner and set the waterer on that. I tried hanging the waterer but they pushed it and the water sloshed out. There is a hole in each corner of the corral low down. These are great for hanging treat and grit containers. I have a small metal pail with a hook welded on it that I just fill with grit and the hook hangs thru the hole. Sooner or later you will need a lid. Use chicken wire. Take some duck tape and fold it over the edges of the chicken wire so you don't scratch yourself when you lift the "lid". Leave about a 3-4 inch overlap on all sides of the lid. Now take a couple of 2x4's and lay them across the top of the lid so the birds don't push up the lid when they get older.
You could also use this as a baby brooder if you had a light in one corner where they could keep warm and the pen was not in a drafty area. Would also cover the half of the brooder with non-flammable material where the light wasn't to help keep in the heat. Do not let the light rest against the cardboard walls.
Best Regards,
Karen