Ok, I've reread this thread and nobody's mentioned painting the ends of the cable red for, say, auto tail-lights.
Shamus, have you tried this and does it work?
I've found a supplier for 3mm cable, which should be large enough for any application and light intensity. (I think)
So, George, your saying if I sand the end I can get a brighter...or a more visible glow
because its now emitting light over a larger surface?
I totally agree that the only way to fly on my new layout is with optics. I've hardwired the ol O-scale layout and I'm gonna do my best to do the HO in a more simple, straight forward fashion, without all the wires!
My 2¢
Rich