Basically, all the pre-manufactured ones consist of a box to catch overspray and a ventilation system to vent fumes. I found some ideas from peeps on the interwebs ranging from a cardboard box (which I was previously using with lackluster results,) to a full on professional auto spray booth. Clearly, I do not need a booth big enough for a real car, but I was able to use a couple of the components of a professional booth to incorporate into mine.
"First," I thought. "How big do I need this thing to be?" I found some advice from other model builders who had built a small booth out of a Rubbermaid tub, turned on its side, and a simple vent system using an A/C fan and some dryer duct. Not bad, but I was looking to go just a little bigger with mine. Fine, plywood and 2X4's it is...
Next, I focused on the ventilation system. Initially, I was planning on simply using any type of fan to create said ventilation. Then, through my research, I realized that I should probably use a proper fan for this (enclosed industrial motor) since an open motor could ignite fumes, and that would be bad. :-p Found some squirrel cage fans, but most had either too high of a CFM rating or price for my application. Then, it hit me.... Range Hood. Enclosed fan, variable speed, light built in, and, with the available sizes, I could get one that would be just right for me. Struck gold on Ebay and got a Kenmore 30" range hood with duct ventilation for $19.99 including shipping. Done.
Hit Home Depot for supplies and got started.
Sure do miss my garage. But, oh well, a workshop is anywhere you build stuff, right? Besides, our current location is cheap and temporary :-)
Cut out my base and trimmed the edges with some 2X2's for stability and nailers (screwers in this case.)
Mounted the side walls. 
Mounted shelf (bottom of actual spray section.) Creates storage space underneath for my airbrush, paints, thinners, cleaning supplies, etc...
More nailers/braces and mounted the back piece.
And just a dry fit for the range hood. I share my current workspace with the washer/dryer and our 5 cats' feed bowls and litter boxes. Needless to say, dust, lint, and cat hair are a very real issue for me. I plan on making a removable face enclosure so that I can seal my work off after painting for drying. So, I will be adding some filtered intakes to catch the cat hair and dust. I have some left over Plexiglas from my speaker box build for the Jeep you see in the background.
That is all I have for today since the heat of the day and the wife's call to dinner has cut this build short. Next step is mounting the hood to the top, making the legs (simple braced 2X3's, same as my workbench build), and enclosing the face.
More to come.....
7/17/10
Home alone with the kid today, so all work has been moved indoors.
Bent out all the flanges for mounting the hood on top.
Added the legs to make it a free standing unit. My workbench already has enough clutter. With the hood on top and the low ceilings in my work area, I had to cut the legs down 6 inches so that I would have room to mount my vent duct on top. Actually works out better, because it was just a little too tall anyway.
I couldn't have gotten any luckier... The leftover scraps of plywood are exactly the right size for the face enclosure and a little door to the storage area.
Plexiglas with trim for the "observation deck."
Cut a hole in the plywood and mounted the Plexiglas unit to complete the face. This will be attached with latches for easy application and removal.
"Completed" unit. Lastly, I will be fabricating an adapter for the ventilation and venting out through the dryer vent with a Y adapter and damper to prevent any backflow of dryer dust.
More to come....
