I have done it with the camo kits you can buy from a sporting goods store and also with rustolium paint you can buy from your local hardware store. Both work real well as I have some markers from the late 80's that still look good. Real important is the prep-clean with soap and water until all oils are removed from you marker and you are good to go. To keep your finish long lasting use a clear flat-semi-or gloss spray for final coats. I usually give them three coats of clear.