Here is my current setup for painting. The air compressor is a Crafstman oiless that is 15 years old. I brought it in from the garage last year when the compressor unit on my much smaller Craftsman unit failed. This compressor is quiet and has more capacity than needed for our work, but it doesn't have to run much once the tank is full. The air line runs into a 3/4 inch copper coil. This allows any moisture in the line to condense since it is a short run to the Finish Line separator/filter (the orange thing).
My paint booth is a large shipping carton I got from U-Haul. It sits on a plastic storage table and can be easily removed if I need the space. A section of the back is cutout to fit around an intake vent in the wall that exhausts through 6 inch duct piping to a 400 CFM blower that is mounted between the ceiling joists and exits the house through a 6 inch diameter dryer vent. Whatever you use for painting you need some positive way of venting fumes; and odor. I use a Park bicycle stand for holding a variety of PVC pipe fixtures for holding rocket airframes. Some merely slip into the motor tube. The fixtures can be rotated by hand to allow easy painting and keep the spray in the booth for evacuation
I have used four guns for painting. The first one is a Devilbiss primer gun with 1.8 tip. The benefit of this gun is it can spray 2K primers without any reducer....in effect, a high build primer. I use it, but have to dial back the needle quite a bit. I typically reduce my primer a tad as the first primer application is a search and fix mission. After sanding and addressing flaws, the next coat sets up the base for topcoats.
The second gun is CATechnolgies Tjr. detail gun. It comes with three needles and cap sizes, but I only use the largest 1.2 size. It does all of my base coat and clear coat work. You have to remember that industry recommendations for needle and cap sizes is geared to shop work painting cars...as is mixing ratios regarding use of reducer. If I had to, I could use this gun for everything on rockets.
The next two guns are Harbor Freight HVLP. The full size has a 1.4 tip. I have used it with 2K primers and works fine with a bit of reducer. It has a very nice pattern for our needs. The smaller purple gun is a HF detail gun. There is no tip size label on it but I have also used it for base and clear coat. If I didn't have the Tjr. this gun would be fine.
Production shop use one of two disposable paint cup systems. Devlbiss has the DeKups system and 3M has the PPS system. The advantage of their use is easy cleanup (you just have to clean the gun), easy measuring right in the container, spray at any angle (works like a baby bottle) and acts as a container for any leftover paint that may have a shelf life after mixing. The only disadvantage is cost. I use the PPS mini cups. A box of 50 cups and lids is $75 dollars on Amazon. The minis hold just short of 6 ounces. The only rocket that required more than 6 ounces was the Ethos 2.0 color coats. That was a tough color to spray. The PPS system was recommended to me by an auto painter who has used both. Im sure either would work fine if you go that route. Bottom line is you need two guns. The most important is your finish gun.
Paint chemistry choice is another topic as is spray setup and technique. An expensive gun will not make up for poor technique or improper adjustment. A practiced painter can make an inexpensive gun work just fine for our application.