I built a temporary booth when I painted my car out of 2x4's. I elected to go positive with air. My thoughts were if I suck air in dirt is going to come in from under the booth. Water on the floor is a must. I sprayed the floor down between coats. For air I put the furnace blower up high on one end and filtered the incoming air through a furnace filter. Then low on the other end I put 6 more filters to catch the paint particles. They were thoroughly plugged by the time the painting was done. Also get a fresh air mask! The fumes from 2 part paints are very toxic and can cause permanent lung damage.