Hobby shop. Get a can of transparent smoke spray. I did a set of clear/reds outta all clears for my gf's civic. Also made a set of red/blacks with the factory ones that I replaced on her car. Check my sig for a lonk to pics of the civic with the tail lights.

Also, spray light coats, and be patient. If you did it the way I did, you get alot of frickin overspray that you'll see, I have to redo them when I get a chance.