I built my last booth out of 3/4 plywood and a squirrel cage fan I got from Granger.
I built a small channel or bracket(For lack of a better term) over the fan outlet for an A/C filter.
I had to vacuum the filter about every ten uses of so to remove dry paint particles.
While it worked well, I made one modification. I added a piece of plywood on top of the open front to make the opening smaller.
I got a lot of paint fumes escaping out the top and this extension kept them in.
When I moved I trashed the booth but kept the motor.
When I rebuild I plan one additional modification, lights in the booth.
Otherwise I found this booth to be quite functional.