I just wanted to say that I had to go *really* cheap for a brooder.
I had hoped to use a fridge box, but couldn't even find one of those.
I had two boxes that were for filing cabinets. I just figured out how much I had to leave to have the bottom, sides, and ends (and a bit of a "lip" of the top edge) and cut the rest of it away. I used the cut away part to make the middle, and the solid box parts for the two ends. I did spend $4 on duct tape to hold it all together though .... LOTS of duct tape and wrapping the whole thing.
I also spent a few dollars on a heavy-duty plastic tablecloth that turned out to be the exact right size to line the inside. I duct-taped it along the top, and it lines the inside walls and floor to make it waterproof and easy to clean (if necessary).
I used an old broken half-cinderblock to raise the waterer (had to hammer the rough pointy spots smooth), and filled it with aspen. (The shavings have been the most expensive part. I heat it with a heating pad under one end, and a craft lamp that I already had over the middle.
Now it has a piece of leftover hardware cloth over the top to prevent flyers.
I will post pics when I can get some developed. It's pretty big though, and only cost about $6 for the tape and tablecloth, and I had all the rest on hand.
In case it helps someone.
trish