I used flame masks from Stickershock to mask flames on a Hawk Mountain Basilisk. The rocket is 2" and all fiberglass. Stickershock supplied two similar masks. One may have been a mirror image of the other. Anyway, same look but different. Each mask sheet had what I'll call a positive (what the flames would look like) and the mask on it.
After priming, I painted the whole rocket bright yellow which was then wet-sanded with 320 to promote adhesion of subsequent coats.
Next, I used the POSITIVE from Mask1 to mask off the upper part of the rocket and painted the lower part chartreuse (obtained by mixing a small amount of green into the yellow paint). When dry, I removed the masking and wet-sanded with 320.
Moving up a little, I applied the MASK from Mask2 and painted everything above that orange. Let dry, remove masking, and wet-sand.
Moving up even more, I applied the MASK from Mask1 and painted the nose of the rocket red. Let dry, remove masking, and wet-sand.
Finally, I sprayed clear over everything.
I noticed that the adhesive on the masks left some residue on the rocket each time. This has to be removed with some kind of solvent. Since I was using Klass Kote epoxy paint, I used lacquer thinner. Of course, you could not use that if you are painting with something that lacquer thinner would attack.