sometime ago I built myself an el cheapo but very useful spray booth. I thought about writing it up as another how-to article but when I got into it, it was obvious that it was not going to fit their format.
It folds up by removing one wing nut on the underside of the top. It takes probably a less than a day to build it. The blower is salvage from an old heating system. Most heating service company will give you these for free out of the systems they replace. The one I have in this booth is an antique, probably about 90 years old, but works very well. newer ones are often direct drive, smaller and put out much more air.
Here is a link to an archive that has multiple pictures of the construction process and the beginning of my article.
The attachment limit is set so low on this forum right now that I could not attach a picture, so I put it in my gallery here is the link
I will be glad to answer any questions about building it.