I know PVC was already mentioned but I'm going to remention it because it rocks. :-)
I had 25 CxR's last year and made an outdoor run for them and they THRIVED. (I still have one thats 7+months old ) Use PVC to frame it and secure bird netting around the outside to keep them in. Mine was 5ftx5ftx3ft when it was inside. You could make yours whatever size you needed. I Zip-tied hardware cloth to the PVC frame on the top of the bottom framing so it was just over an inch off the ground and poop would fall through onto a mat I made. Just took some of that cheap floor covering, i think its either vinyl or linolium and comes in rolls and secured it to the ply. (I used spray glue and a squegee because it was handy since my husband installs A/C). I would just pull the matt out from under it and hose it off every night. Worked like a DREAM. Once they got to be about 3 weeks old I took the PVC enclosure outside and flipped it over so they could be on the grass and the hardware cloth kept them in, I ended up adding another 5x5x3 section to it making the entire enclosure 10x10x3. Put a tarp over one side for shade. The PVC support across the top of your frame gives you somewhere to hang feeder and waterer.
It was actually really simple and I cant see doing it anyother way now. It was light enough that I could move it by myself whenever their spot got kinda poopy. And it'll fertilize your yard. ;-)
One thing I had to do with the bird netting was notch the PVC where I was putting a zip-tie so that it didnt move around and kept the netting taught. It works great.
Good Luck. Let us know what you end up doing!! Post Pics!