I would definitely use PVC for the frame for starters....Especially if you are using sheet....I also suggest using either a grate, or epoxy based flooring...The Epoxy will be easier to keep dust free, if the booth you are making isn't huge....I just got done building a booth at my brother's house....We built a pretty descent sized booth with a 4 fan system...We went to
www.americangarage.com for the flooring and paint cabinets and stuff...We were really happy with what they had to offer....I hope I was some help, good luck buddy