The usual order of operations
- Remove supports carefully — flush cutters first, then clean the scars.
- Sand progressively — 120 → 220 → 400+ grit, wet-sanding for a smooth finish.
- Fill and prime — filler primer hides layer lines; sand again between coats.
- Paint or coat — acrylics with a clear topcoat, or a functional sealant.
- Optional: vapour-smoothing for ABS (acetone) melts layer lines into a gloss.
Match the effort to the job
A functional bracket needs supports removed and edges deburred — nothing more. A cosplay mask or a display piece earns the full sand-prime-paint treatment. Deciding this up front saves hours.
Food and skin contact
FDM layer lines can trap bacteria, so 'food-safe' filament still needs a food-safe sealant for repeated contact. For anything worn against skin, choose a smooth material and finish, and round every edge.