I like this idea, there are some creative people out there!
Today I used a quick and cheap way to identify my keys for easy identification with nail polish. I painted the top of each key a different color of nail polish. You can paint the entire key if you want, but I like just painting the tops.
After the key dries, you can leave the colors the way they are or if you want to make them look edgy, add a crackle polish finish to them. The crackle polish adds a cool effect.
When the crackle finish dries, finish up with a cover coat and let dry. The keys will all be color coded and hopefully, save you a little time next time you need to find your key quickly.