Here's something I cooked up a few months back. I was interested in getting a spray booth to assist extract the fumes from spraying in my man cave, and had read that the small, computer fan style extractors didn't provide enough cfm displacement for the sort of spraying with lacquers I normally do.
I did some research and found that a conventional 240V bathroom fan is very good at moving air. I also found that flash-point/explosion risk is generally pretty low, especially with a good filter and a centrifugal style fan system like this one, so that was good enough for me to give it a crack (please do your own risk assessment before building your own!)
Here's all the stuff - I bought the fan on Ebay for about $40 from China, along with the roll of filter material, hose and window connector. The black tub and LED light came from the local Bunnings. I went with a pretty decent sized one (75L, or 740mm wide x 465mm high x 280mm deep), as I wanted the space to handle larger jobs (maybe 600mm wide.
I then cut the hole to the right dimensions with a fine angle grinder blade and fitted the fan unit.
Next add the layer of filter material, place the cover over the fan, and attach the hose unit:
Almost done. Just got to set it up on the bench, screw in the LED light source, and connect the hose to the window:
It works a treat! I plug it in a few minutes before a spraying task and it seems to suck all the dust and nasties in the immediate area of the room before you start adding paint to your project. It's powerful enough that you can see the vapours being drawn into the unit, and the amount of reside/overspray is minuscule compared to the layer of paint 'dust' I once ended up with on every surface. I have taken to lining the base of the tub with Chux wipes, and placing the model on a a small cake decorating wheel base to allow 360-degree rotation of the model while spraying.
Thanks for viewing.