I haven't given it a go for a few months, I tend to try something new (eg.stamping, foiling) get frustrated then pack it way for a few months before trying again! I've now mastered the stamping and foiling so will have to give the sharpies another go again now. I tried them on nail polish and gel polish, would remove inhibition layer on colour coat, scribble the sharpies and then dot on IPA with a brush, could usually still see the scribble lines though and it just looked a bit naf. I've since bought a new LED lamp which is more powerful and setting my gels properly so maybe the problem was that the colour coat wasn't quite 'hard' enough.. We shall see when I try again!