Testors enamels! (testors.com) Yeah, surprisingly, those little 1/2 ounce model paints we used as kids. With good prep on the calipers these paints are known to work well, even with the heat calipers generate, and come in any color you can imagine. Some people use a final clear coat (not me). You'll need a bottle paint per caliper. Good prep means lots of brake cleaner spray and light steel brushing. Mask any mating areas. Let paint harden for two days before driving.

I used these on my 855T, 95 twinturbo rx7 and a Ducati and lasted many years with minor touchups. BTW, there are special caliper painting kits...from places like TireRack if that's what you are more comfy with, but offer limited color choice and quite expensive. Good luck.