*FYI, do NOT use the black RIT dye if you want to see the letter labels. Black dye will very effectively blank your keys.*
I dyed my model m keys using rit dye, and i promise you that you won't melt the keys as long as you stir the mixture constantly. Don't be afraid to let the water temp reach and stay at boiling (my dye made NO progress until the mix reached a rolling boil), add some salt to the mix to help colorfastness, and rinse with CLEAN COLD water when finished.
Be CERTAIN that your keys are completely clean of any skin oils, dirt, etc. Dirty keys = crappy dye job. I soaked mine in a mixture of hot water and simple green for 10 mins, rubbed them thoroughly with a cloth, and then soaked them again in a 20:1 water/bleach solution, rinsed, and only handled with rubber gloves until the dying was complete.
As for paint, I used Krylon Fusion Satin White for the outer case, and Rustoleum Industrial Machine Gray for the inner case (the area immediately surrounding the keys that is recessed at the bottom and sticks out from the case at the top). I prepped thoroughly with the same simple green / scrub / rinse / bleach / rinse regimen mentioned above. Neither paint has peeled, chipped, or even shown the slightest signs of wear. My only regret is that the simple green or bleach solution caused my Lock Leds label to begin to peel, so I'm now without a label in that position (I thoroughly removed all adhesive and painted it along with the rest of the case, so it's at least a nice clean look)
I apologize for the novella, but having experienced this recently, I thought I could share some of my experience in this area
edit: adding a pic of my keyboard for reference
