You can find nearly any type of automotive bulb in its LED configuration somewhere in eBay. I have tried them in several cars, and I have two problems with them:

1. They throw light straight out the back, but none to the sides. This means that the reflectors in your housings do nothing - you get a small bright light, but not the bigger light that you'd see if they also directed light towards the reflectors.

I hope some smart company has realized this by now and is selling a better-designed bulb.

2. So far, they only come in red. Having a red light behind a red plastic lens is overkill. We need white light!

Also, apparently some companies have recommended you use a special resistor inline to lower the voltage to the bulb, and now a lot of people think you MUST do this. Those bulbs are long out of date. Find newer ones that don't require messing about with your wiring if you can.

One last note: You can run most of these bulbs on 6 volts without any trouble. Check to see what voltage range they operate under.

As far as casting tail lenses, I think it's a great idea, although it will probably be fairly tough to get a good product due to the Fresnel bumps inside them.

We only learn if we try, whether we fail or succeed is only a result of the amount of work you're will to put into a project.

Good Luck!

Stevv\e