http://www.watsons-streetworks.com/leds_plus.html This is the place I have used in the past. There is a company that sells the chemicals to mix to make you own LED's. It was called EDGAR Plastic, but I believe they were bought out by Berry plastic. What was awesome about this is you get on AUTO-CAD make a design, mount your led light board mix the chemicals, and pour your new one-off lights. any color any shape sanded down smooth to match the contoutrs of the body. I never used the product, but have seen many trucks and bikes with some pretty wild tail lights
http://www.custompainting.com/taillights4.htm