Those are some nice brooders, but to the OP, it doesn't have to be anything fancy - or even a major building project. Mine is just an old laundry tub (3'x18"x18" deep). I fashioned a top for it out of chicken wire, rest a red light on the chicken wire at one end, and it works great. Years ago I kept rats and made a cage for them out of a large rubbermaid container. I cut a large window out of the lid and covered that with hardware cloth. In the event I had to brood a second lot of chicks while my first brooder is occupied, I could just pull that out of storage and use it. I recently bought chicks from a lady who had a brooder in her chicken coop that was simply 4' long boards, about 18" high, nested together to make a square, with a light hanging over the whole thing. When the chicks got to be big enough to jump over the sides, no problem. The whole coop was well ventilated but draft free and they were able to just hop in and out as they pleased.