Loco lighting on 12V DC has certainly changed!!! Last time I worked on such a project, we were still looking at constant lighting circuits as the Bee's Knees. Indeed, in order to get the kind of lighting effect I wanted (white LEDs were still in development) I'd dabbled in bulbs used in medical equipment exam scopes (mini halogens)! Alongside, I also invested a bit in some fiber optics to offset attempting to illuminate something a bit out of the way like ditch lights or a roof beacon. So, my Q is, given the advances in miniature LEDs and the ability to eliminate bulky constant lighting circuits in DCC, do you still use fiber optics in your locos (or elsewhere)?