I have some bushings that I bought from a fella that he had marked the size on with some kind of marker. It appears to be some kind of ink but seems to stay on very well. I have a complete set of PW bushings that I would like to mark the size on as well as several Hornady bushings that have very small stamps. Any body have any idea what he might have used to mark these or what to use. Don't want something that will rub off and don't want to use paint.