[watahyahknow]

i've seen a drawing in the hot rod magazine a while back where they made a frame with some 2 by 4 's stuck straight up in a buckets of concrete with some smaller beams across and a tent made from clear plastic sheeting
they used a normal standing fan through a hole cut intoo the plastic ......... it should work ok and might save some time on dusting off the shop to prevent anything from landing in the paintjob .

things i usually do is wet the floor to catch any left over dust from blowing up when walking past the car with size elevens painting the sides and hang a chain from the car to the floor to prevent static electricity from blowing up the place when spraying high flamable paint and solvents in the air