You can pick a can up at most auto stores. Its like 7 to 11 bucks. Ive used it on 2 different sets of tails and a few friends. It works good if you prep them first. Just make sure you clean them really well. And if you want when your done you can clear them. And then polish them.

Another thing you can try if you have acsess to automative clearcoat, is just add alittle basecoat into the clear and just apply as many coats as you want. Thats how i tinted my turn signals and tail lights, accept i added black to the clear.

Also dont forget to adhesion premote the surface so it dosent flake off after a couple months.

Had this stuff on my tails, front turns and front corner lights for a lil over a year now and just the other day added it to my headlights as well, Cleaned the parts with wax/grease remover let thoroughly dry then spray, hit it with a cpl coats of clear to protect it and call it done.
Actually come to think of it I used this on the handle of my floor shifter too (HATE chrome) gave it a nice "black chrome" look, like it MUCH better than fugly shiny silver.