Required materials: Folia Tec brake caliper lacquer 1" fine natural-bristle brush wire-bristle brush container to mix paint popsicle/mixing sticks masking tape & newspaper lacquer thinner (for cleanup) Costs: about $60 for kit and other materials a few hours time
As you can see from this picture, the stock calipers really don't stand out at all, even though they are good-sized. I had seen other cars with bright glossy calipers (yes, even P-cars...shhh) and I liked the look. When I found out that Folia Tec made lacquer specifically for brake calipers, I had to try it out.
The Folia Tec kit comes with a can a lacquer in your choice of color (I chose red, but yellow, blue, green, black, silver, gold (shudder), etc. are also available), a can of "hardener", and a spray can of brake cleaner. Before beginning, put blocks behind the wheels of the car, make sure the handbrake is set, and jack up the car (now might be a good time to call BMW and complain if you are an M roadster owner without a jack).
The instructions say to use the supplied brake cleaner and the wire-bristle brush to clean any brake dust off of the caliper. Clean it well--you don't want anything to come between the paint and the metal of the caliper. Be careful to avoid damaging any rubber parts towards the rear of the caliper with the wire brush. After allowing the caliper to dry for a few minutes, you should mask off anything you don't want to get paint on (if you're too lazy to remove the caliper from the car, like me!). Don't forget to put some newspaper on the floor under the caliper to prevent drops of color on your driveway or garage floor.	(Now's a good time to see a cool detail I hadn't noticed before about the M calipers--the nifty ///M cast into them.)
Before you can begin, you must mix the paint and hardener in a 3:1 ratio. Since I didn't have a lift and was doing one wheel at a time, I didn't want to mix the full contents of both cans all at once. I just eyeballed the amount I poured out of each can into my mixing bucket and it seemed to work out fine. After stirring the paint and hardener, wait 15 minutes and stir it again.
Use the brush to put on a thin even first coat. It will start to harden quickly, so quickly brush out any runs or drips in the paint. The rear of the caliper is hard to reach, but you can't see it when the wheels are on anyway, so don't worry too much about painting there. I'll appreciate no giggles about my masterful masking job.
Let the first coat dry for 15 minutes and then apply a second coat. After the second coat, let the paint dry for one to two hours before replacing the wheel. If you are doing the job with one jack/one wheel at a time, you will want to rinse out your brush using the lacquer thinner now, or it will be completely stiff by the time you get around to doing the next caliper.
The final result is, in my biased opinion, pretty sharp. I hope some others out there try this kit as well, as I'd really like to see some of the other colors. I believe Folia Tec even makes a chrome-look caliper paint, which would look sharp on a certain monochrome car I know...