I have used the gum lables as dgraham1311 described and they work quite well. particularly when you are preacticing shots over & over and want an easy way to reset the balls. Works well and I do not see any noticable interferance on the balls. For lines I have used white medical tape, which you can purchase at any drugstore. I got the tip from one of the Byrne's educational videos. This works quite well, also with no noticable interferance on the balls.