Burning of polyurethanes and plastics is nasty and Isocyanates are only part of the concern as it also produces cyanogenic compounds (like hydrogen cyanide). A few years back now, there was a typical car-b-que in Dallas. Usually the guys stand back and do not don SCBA's since it's outside. This time it was a Pontiac Fiero (remember the plastic body?). There was a wind shift and several fire fighter received "minor" smoke inhalation - and died relatively quickly. Subsequent/forensic analysis showed elevated levels of hydrogen cyanide and was confirmed with some test burning. Test burns are pretty interesting - if you're interested I could related a forensic where the Texas Department of Insurance (that's where the fire marshal's reside) caught a woman committing a homicide and covering it up with a fire - by burning a 450 pound pig carcass (it's gross), but I'm digressing off paints and jets.

How about designs of home-built paint booths? I'm about to turn a 3rd garage bay into a down-draft booth that will quickly convert back to storage for my Cobra. I'm interested in what others have done as well.