Spray max comes in many colors. Some shops can also premix paint for you in a spraymax can as well
Ive used both spraymax and spray guns and if you are after pro results there is no substitution for a spray gun. particularly if you start doing any volume it ends up being much cheaper. Like anything with a large industry dediated to it there are a million different opinions and ways to achieve good results. Some guns will have a built in regulator, but this more for ease than anything else, the regulator on your compressor will be fine. you need to run a water/oil trap at the bare minimum. a airbrush specific compressor is nice because they are quiet.
These are some things that i have found work well for me.
Astro LVLP guns (Not to be confused with HVLP) - 1.4 tips - 1.6 for epoxy primers really good for painting medium and small stuff. I know a lot of folks have had good success the the HF HVLP guns.
Iawata Eclipse dual action airbrush. - dual action is where its at for airbrushes. I prefer siphon fed over gravity on airbrishes because its easier to control the tool with the COG lower, aslo they typically have bottles you can switch out quickly without cleaning the tool.
Use separate gun for clear only
Use an inline desiccant filter right before the gun.
Get the good gun cleaner spray - its worth it.
buy low lint paper towels for prepping - i use Kimtech wipes
Good wax/grease remover is worth it.
Read the tech sheets and FOLLOW THEM.
I've never regretted spraying a test panel.
Its always worth it to make a fixture to hold gas tanks and get them off the table so debris don't blow up on the piece.
Buy the best paint you can afford. I have had good luck with PPG Deltron line but its not inexpensive.
DO NOT MIX PAINT LINES DESPITE WHAT THE GUY AT THE PAINT STORE TELLS YOU - looking at you Lakecity Wesco!
If you do, do a test panel first. - sometimes it will look OK but the clear is just sitting on top with no crosslink and will flake off when you flex the panel
a lazy susan makes it very easy to paint round objects.
when spraying clear, less is more. Just spray till its wet, going too thick can cause curing issues beyond the obvious runs and sags. Its better to do multiple thin coats rather than 1 thick one.
Isocynate clears are very toxic, spray guns have better atomization and will fill the air with fumes better, sensitivity increases with exposure - be aware, always use fresh filters and shave for a good seal before spraying clear
Use PVA gloves when cleaning up gun - you only got one liver.
This is a really important one - Use water based auto paints when painting helmets. The solvents in many paints will melt the foam or degrade the helmet shell. IIRC any modification to a helmet, including painting, voids its DOT rating which could raise liability issues in an accident scenario - be aware