It's nothing new, but I didn't see a thread on this yet so I figured id start one. I recently did the color fill on my m&p shield and it came out so good, I did my G19 and my AR lower too. Just thought id post some pics! I went with the nail polish technique because it was readily available (my wife didn't care for it to much though) and because I felt it would outlast a crayon. ENJOY!