No FDM print leaves the bed ready for a display shelf. Layer lines are built into the process, and seams and zits are part of the deal. The gap between a "print" and a "product" is the post-processing you put in. Here is a practical, order-of-operations guide for taking parts from rough to finished.
Step 1 — Clean and De-Burr
Cut off brims and supports with flush cutters, scrape a deburring tool (or a hobby knife held at a low angle) around edges, and remove stringing with a heat gun on a low setting. Never skip this step — it defines every line afterwards.
Step 2 — Sand the Layer Lines Away
Start coarse, finish fine. Moving through 120 → 240 → 400 → 600 grit works for most surfaces. Sand in a circular, lapping motion rather than one direction, and wet-sand from 400 grit onward to keep dust down and plastic surface smooth.
- PLA — easy to sand; use light pressure so heat doesn't gum the paper.
- PETG — slightly gummy; wet-sand from 240 to avoid smearing.
- ABS — sands beautifully; the most forgiving of the three.
| Material | Start Grit | Finish Grit | Mistake to Avoid |
|---|---|---|---|
| PLA+ | 120 | 600 | Wet-sanding too late |
| PETG | 240 | 600 wet | Dry sanding at high grit |
| ABS | 120 | 800 | Grit jump too large |
Step 3 — Fill and Prime
Wood-filler or model putty hides layer lines instantly on flat panels. A few thin coats of primer (spray or airbrush) seal the printed surface, fill micro-furrows, and give paint a footing. Allow each coat to fully cure before sanding with fine grit.
Step 4 — Paint Like a Pro
- Mask off areas you want to keep unpainted.
- Apply thin, even coats — several light passes beat one heavy one.
- Finish with a clear coat (matte or gloss) to protect the colour.
- Let the piece cure overnight before handling.
Acrylic paints and hobby-grade spray enamel both work on PLA/PETG/ABS. Avoid automotive solvents on PETG, which can craze the surface.
Step 5 — Fume-Based Smoothing (ABS/Castable Only)
For an ultra-smooth, glossy ABS part, vapour smoothing with acetone dissolves the outer skin and fuses layer lines. Do it outdoors or in a fume hood only, and never on PLA — acetone attacks PLA's structure and turns it brittle. This is a finishing step best reserved for ABS when a flawless shell matters.
The Tool Kit Worth Owning
- Flush cutters and a deburring tool
- A hobby knife with a fine blade
- 120–800 grit sandpaper, wet and dry
- Wood-filler or model putty
- Primer and acrylic paints
- Clear coat and a low setting heat gun
- Safety: dust mask and nitrile gloves
Finishing Is a Material Conversation
The easiest part to finish is the one printed with a dependable base material. Start that conversation with a clean, consistent ANTINSKY PLA+ Filament for easy sanding, move to PETG when you need toughness, and reach for ABS when you want glass-like fume smoothing. Print it, sand it, paint it — and put it on the shelf.