DIY quality paint job
"exhaust fan."
You guys would be FAR better of "turning your fan around," so to speak
Use a SUPPLY fan IE a outside air inlet that is HEAVILY FILTERED, through which the fan SUCKS clean filtered air and blows that INTO the booth, then an "open" duct out the top/ side where exhausted air can flow
WHY is this better? Because an INLET (supply) blower can ONLY get it's air through the filters, and because it is keeping a "slight positive" pressure in the booth, dust cannot infiltrate under doors, through cracks in the constrction, etc.
This would be especially important if your garage/ shop is on a dirt alley/ road with some traffic.