I found this youtube video of a better homemade garage paint booth. I would think that you could design the peg board idea into the ceiling for the incoming air also. I would also use finer micron filters and use more of them and possibly 2 fans to pull the air out of the lower box. Definitely reinforcing the peg boards to support the vehicle weight. Design enough space around you vehicle also maybe 48"? LABAP videos show painting in a garage without any booth.
Definitely need a booth of some type imho.
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https://www.youtube.com/watch?v=djFjaANin7w
