Mods, please move this if it doesn't belong here (and if you could, let me know you moved it).
On one of the gun forums I frequent (i thought it was this one), people had advice for coloring in the markings (logo's, fire selectors, etc) with a variety of different items (some kind of pen, crayon, nail polish). I did a search, can't find it. If someone happens to know, can they post a link? mods, maybe make it a sticky? It was a thread that was pretty long, with a boatload of pics.