you can use burnishers, very fine abrasive sticks, tooth picks, lotsa things. do a bit of experimenting. decide what works best for you and go with that. chris decamillis sell such abrasives. check out his site.
I make mine out of modified Allan wrenches. Grind the short end to shape and pull them back.i also use tiny scrapers that i use to pull, rather than push. fewer disasters that way.