I used plastic, wet floor.

For ventilation, you will need at least two box fans, possibly 4.

I framed an opening in my plastic walls for the furnace filters. I had twice the intake as I did the exhaust. In other words, two fans, four filters on the incoming side. The fans are configured to suck out the paint fumes, I would never blow anyting into your paint booth.

Also, I put filters on the exit fans to try & keep the "cloud" from simply blowing out into the driveway. That way the only thing escaping was the smell. Clear reeks, the regular paint barely has an odor.

Make sure you have several layers of plastic at one end that function as a door so you can enter and leave. Try & disturb the plastic as little as possible. Paint will not adhere real well to the plastic and will drop off onto your beautiful new paint job if you rattle the plastic too much.

Even with a wet floor, you will end up with a discolored floor. So, if you don't want your floor to match your car, put down paper or something similar.