I'm very tempted to give it a crack - Calumet are listing a changing bag for Ł17ish. I'm going to see what I can beg/borrow/steal from others (tank/reel/tubes etc).

Who knows, I might even get started by Christmas!

Ooh! Another idea. Photographic paper - can you just dump it in tanks (load in dark bag, then do chemistry etc in daylight as per film), or does it need something flat (trays) to do it properly? Just wondering, as I'm thinking about building a LF pinhole and paper is WAY cheaper than film