A nub mark is the blemish left where a nub was removed: a small raised bump, a shiny flat spot, or a pale stress mark against the surrounding plastic. On dark or clear parts it can read from across the room.
The fix is a sanding ladder — 400 to 600 to 800 grit and beyond — feathering the spot until it disappears into the surface. On unpainted builds, finishing with a fine polishing grit restores the plastic’s original sheen.
See it in context in our nippers & cutting tools guides, or explore the tools hands-on in The Bench.