Building my own Paint Booth

My booth is about the same size as yours. 32L x 18w x 24H

See my post about a possible source for a fan.

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Search this forum ,I know there is a lot of this info on here.

Here is my setup...

I built my own a while back, it's a little wider than your, ht/width about the same. I used a bathroom exhaust fan at the top, vented outside. For the size, it works quite well.

I used a five inch muffin fan, used to cool electronics.  They come in a wide range of capacity- you want at least 100 cfm (I got a 120 cfm unit).  My current booth is my third booth using muffin fans, and is a keeper. It uses furnace filters (replaceable).  Earlier versions used auto air filters- the furnace filter is much better, and cheaper if you buy bargain units on sale at home improvement stores.