After constructing 4x5 film developing tubes based on the instructions in Phil D avis' "Beyond the Zone System," I was going to build some tubes for 8x10 negativ es, which require 3" diameter ABS or gray Schedule 40 PVC tubes. My only proble m has been that I've hit a brick wall in trying to find that kind of tubing in t he Chicago area. Apparently, ABS is not used very much anymore, and everyone in this area seems to use white PVC pipe, which is unsuitable for the film tubes. Does anyone have any suggestions on where I could track down appropriate tubing in the Chicago area or through mail order? Thanks very much.