We set up the following out door paint booth and bought the following equipment to paint my son's 67' Ford Galaxie engine compartment and inner fenders.
1) We built a copper pipe air dryer and it worked great. Never had any water issues at the gun. Ran hose to the dryer, then a 50' to the painting area. Our friend has a large air compressor so CFM was not an issue.
We picked up everything for the dryer at Home Depot. I want to say we paid around $325.
a) Used a sheet of 3/4' thick plywood. We decided it would all have to fit on one piece and we would fasten to the plywood with pipe holders. That way it was portable/movable.
b) 3/4" copper pipe. Many suggest it has more surface area than 1/2 inch.
c) 3/4" hose bibs as the drains. It has 3 different lift/fall sections with a drain at the bottom between sections.
d) Air enters on left at top and exits on right on top.
2) We used a 20'x20' tent with 6mil visqueen for the walls and floor. Used three box fans with 24"x24" air filters on one side and three 24"x24" filters in a wood box frame on the other side. There was decent ventilation and the filters caught a good amount of the overspray. We used a heavy duty air respirator and safety glasses when spraying. Sprayed each coat and left for 15-20 minutes to let the air circulate and the overspray dust to get sucked into the fan filters.
3) We used a Iwata kit from Eastman.com that was $200, but it did not really spray in a fan, rather it sprayed in a circle so a little disappointing. (I did try adjusting to no avail.) It did the job but I wanted something we could paint the car with down the road. So will have to see if Iwata has a different fan tip that will fan out to better paint the exterior.
4) We found a used professional desiccant system on OfferUp.com for a paint booth. I believe it was by DeVilbiss and then bought the recharge kit. We did not use it for the engine compartment but will use it on the exterior paint job.
5) We tossed the visqueen used for the floor and saved the sides for future painting. Outside of a little overspray on the tent edge at the top, you could not tell anyone had painted.
We used the Eastman.com mid range rust encapsulator which is black in color as the base paint/primer. Which I liked so when we shot the flat black top coats, if we missed a spot or two, you would not see grey encapsulator or grey primer. Both paints shot nicely and laid down nicely. His engine compartment came out great. It will be fun for my son to lift the hood for his buddies and then have them see his ford blue 390 with chrome trimmings pop against the deep black engine compartment. (VS this awesome new engine against a dirty, rusty, and in parts faded old black engine compartment.)