You might look at the strings of small LED lights made for 0 scale Christmas trees and similar holiday decorations. I ran across a set of 25 lights, in R-Y-G, sold by Dept 56, cat # 52728 which have a similar shape to the globes in your photos, though without the optional wire guards; I bought these many years ago at a post-holiday 75% off [ or similar ] sale. They are powered by 3v batteries or equivalent. These have been discontinued for some time but there seem to be others readily available; not sure how you would get the clear / "white" light other than by removing the color of the globe if possible. The lights each have a round plastic black base which could be painted silver; if you inserted the lights through holes from inside the cab that would hide the wiring the resultant effect would be good, less the guards and pipe bracket portion; the latter is easy, but I think you'd need fine music wire and very good hands to do the guards.
You probably know the following, but just in case....
- These lights are [ or were ] often referred to in heavy industry [ steel mills etc ] as "Lintern lights", after a manufacturer; they are also used on overhead cranes or at fixed locations.
- In a typical loco radio control application Green indicated Forward direction enabled; Amber, Reverse; and Red, loco brakes applied [ or at least commanded...]; while F & R would be mutually exclusive, you would have Red + a direction if the brakes were applied. The 'white' light has different applications, but often indicates the trainline brake is charged [ > n psi ].
Have fun !
SZ
