Conrail GP15-1 build... JUST DO IT.

[doctorwayne]

If you want red, MV Products offer small lenses (5 1/2") for class lights - they also have green, white, yellow and, I think, blue.

Here's the white lenses in both the class light castings and the number boards:


My preference for class lights on diesels is to use a .025" strand of fibre optic. Cut a short piece, then hold one end near (without touching) a heat source, such as a soldering iron. It will deform into a mushroom-shaped lense - the amount of heat determines the size. Drill a suitable-size hole in the body shell, countersink it with a larger bit, then install the lense. If you use working lights in your locos (I don't), you can use longer strands and actually light the lenses.
Here are the fibre optic class lights, in the green stripe above the number boards:


Wayne