If you are artistic and very careful you can shape the head of Olympic rivets with a dremel tool and cut-off wheel. Trim the stem very close with a share pair of side cutters first. I know, it isn't like a shaver, but if you only have a few it might be worth a try. You must be very careful but you can make them look almost factory up close and from 10 feet no one will now but you.
Put a little sealer on the rivet shaft before you rivet in into place.
Bruce & Rachel
68 Trade Wind
2001 Toyota Tundra