Cool man have fun. Use the gravity gun. At minimum, you going to get a base coat, the base maker (catalyst to activate the basecoat) and some clear coat & clear coat hardner. Mix them acordingly! or they will never work right. its like chemistry class shit.
Is the bumper, skirts and lip plastic? If so you need a flex additive of the paint will crack and flake right off. Are they primed/painted another color (properly) already? If so take a grey scotch brite pad and wet sand the entire piece, make sure to get into the nooks, crannys and lines. when its completed right, it will look like a matt colored finish. Remove ALL sanding marks prior to scotch brite… paint will magnify sanding scratches big time! 400 grit or higher prior to base coat.
Fill the gun up, with the mixed materials. Set the PSI on the guns regulator to the recommended psi on the paint can. (water seperator is a must also BTW between the compressor tank and your gun) Grab some masking paper or something to test fire the paint out of the gun and set the spray pattern. Adjust the needle, and paint feed adjustments on the gun body to give you a nice 4-5" tall () shaped spray pattern. just point it at the paper and blip the gun for a second full throttle. the top and bottom of the spray pattern should be about 1/2" - 5/8" wide or so and the center should be no more than 3/4" - 1" wide. thats a good pattern for spraying bumpers and what not.
if you never painted before you need to have about a 30% overlap between each pass, slow enough to cover solid, but fast enough to not run. solid basecoats can be shot in 2-3 light coats. dont try to go professional and try to shoot a single solid coat… it wont happen. Metalics are a little harder.
clear is a different deal. You need to make sure you keep the entire surface wet as you paint and shot each pass. if you dont the edge between each pass will dry it and not let it self level the material and it will look like balls and you will be set sanding, cutting and buffing the crap out of it to make it right. Example spraying a hood, DONT spray a hood starting at the top, and makeing 10 passes to get to the bottom, and realizing you missed a spot back on the top and go spraying the spot again. that will do exactly what you dont want to do. Key to clear is keep it all equally wet start to finish the best you can without making runs or dripps.
have fun.
this has been a KrazyKid auto body 101 lesson. Please leave through the doors on the left, and kindly drop a dollar or two into the hat.