I mentioned this project a looong time ago...I was going to post plans/blueprints, but I built it as I went, and had to change some things along the way so it's kind of Frankenstiened together, but this should give you an idea of what you can do. (The original plan was for it to be able to be disassembled without tools for when I move, but that didn't work out.)
In a nutshell, it's a 16' x 4' galvanized roof over the hutch, and the whole thing is angled to fill two 55 gallon rain barrels. It holds 6 30" x 30" wire cages, and produces a decent amount of compost underneath.
