Bob,

Model car builders have been using indoor paint booths for years. Most builders make their own, but there are specialty companies that sell complete indoor booths for hobbyists.

Try and get your hands on an issue of Scale Auto Enthusiast magazine (you can find it at any Barnes and Noble store) and check out the classified ads throughout the magazine. You're sure to find a booth manufacturer in there. Actually, here's a link to an indoor booth available on Micro Mark's website; indoor paint booth

If you are particularly handy, here's a link to a how-to article about making your own booth; make your own paint booth

Good luck,

Bob Jordan