I forget who it was, but someone had done their lettering in red. It was crayon, and luckily easily removed. It didn't look very good (IMHO). It was too dark for the black slide. Hard to see. Overall, if you want readability, you can't pick a darker color (red, blue, brown, forest green, etc). It just won't visually "punch out" from the slide well enough to see/read.
I've done mine in white (which is nice looking), and yellow (not as nice as white). Both Crayola-versions.
I do have a silver lacquer stick that I did my fiancee's gun with (silver lettering on blue slide). I'm seriously considering using silver on my XD, for a permanent coloring. Maybe not all the lettering at first, but at least the logo on the top to start.
As far as a color to go with the green frame, I'm not sure. Maybe a tan? I'd think some sort of "nature" color would be best, to stay within the natural color realm. I think a green wouldn't show up very well, unless you use a lighter green. Perhaps a light gray even?
I'd suggest getting a big box of crayons, and testing different colors out. I've done that w/ a few colors, as I've mentioned. You can then take a toothpick and "dig" the wax out and try something else.
The good thing is: it's easy to do, and easy to remove.
Also, you could maybe get the slide Gun-Koted in a desert tan. I've seen that before, and it's sweet.
http://www.pistol-gear.com/XDET with rock.jpg for this, w/ the lighter colored slide, you'd open up your world of lettering colors a lot. You could then use a forest green (or match your frame color), brown, even black, successfully I think. A lighter colored slide and dark lettering would be nice.
Just my 2¢. Hope it helps. Sorry for no pictures of my colorings. I've seen some other colors before, I just forget where off-hand.
