Quiklilcav wrote:I agree with Machzel about them being annoying, but also if you're not that electricly inclined, the timing circuit would be above your head to begin with.
As far as just doing the LED's, you should be able to find a strip on any one of multiple sites that sell such things, like superbrightleds.com, and mount it inside your window. If you want to make your own, just get a handful of LEDs and resistors, and a long piece of clear square acryllic stock and drill a hole for each LED, then wire them up. I don't remember the value off the top of my head for most LEDs, but it's somewhere around 350-400 ohms per LED. You just wire one resistor into each LED negative side (cathode), then run to a ground. The positive side (anode) gets run to the positive wire from your current 2rd brake light.
The resistor value depends on the voltage drop on the LED you chose, but most 5mm red is around 2.6v.