But some ideas..

http://adventuresinmodeling.blogspot.com/p/airbrush-booth.html

for the information. My booth will be for painting will be for both water based and solvent. My fan motor is isolated from the fan but takes up a lot more room, thus looking to mount it out of the way. Down draft has been my "best" idea so far.

I mounted a bathroom fan inside a shallow heavy duty rubbermaid tub, and vented it out the side of the tub. I cut a hole in the lid and added a piece of heavy mesh over the hole, then built the booth shielding out of Lexan. Bathroom fans are induction motors...no spark.

Got my spray booth done! It's a down draft with a old furnace filter set in a space between the bottom of desk and fan. Lined the inside of the booth with poster board for over spray. Has suction you won't believe. The dampers on the outside of the building are straight out when in operation. I use a small wire grid in the booth to hold objects off the floor. Being a down draft I can't cover the floor of the booth but have had no problem with this setup. Exhaust through the wall with less than a foot of 4" PVC. worked great first try, that's scary when it works right the first time! Sure sign somethings wrong! LOL Hope every one found what they wanted under the tree and enjoyed a peaceful and blessed CHRISTmas. Wishing you a Happy New Year also.

Bing, I'm sorry I didn't notice this before now, but when I was researching paint booths about 6 weeks ago, I was told that the downdraft models (as I believe the Micro-Mark booths are) can tend to clog the filter faster, since so much of your paint is falling into the filter.  I'm really glad to hear that yours is working well for you though.  Even if you end up having to replace the filter more frequently, at least the cost and time involved should be minimal since you're using standard furnace filters.  Sounds like a good decision on your part.

Wanting to take the easy way out this time, I ended up buying rather than building.  Got a booth from Pace ( http://pacepaintbooths.com/pace/ ) based on a recommendation on the Yahoo Proto-Layouts list.  Haven't had a chance to try it yet, but I hope to soon.

When we built our house I had the builder put a vent in the wall in one corner of the workshop to accommodate a spray booth.  I had one I built using the Odegard article in MR decades ago.  Unfortunately it is too wide for the new space, so I'll have to recyle the fan (squirrel cage from Grainger) with a new enclosure.