How to Paint 3D Prints: Priming, Painting, and Finishing

You've printed something you're proud of, a figurine, a cosplay prop, a decorative piece, but it looks unmistakably 3D-printed. Layer lines, visible infill patterns, maybe some minor artifacts. The difference between a raw print and a finished piece that looks injection-molded (or hand-sculpted) comes down to one process: paint finishing.

I've painted hundreds of prints over the past two years, from quick rattle-can jobs to multi-day airbrushed cosplay armor.

Step 1: Sanding, The Foundation

Paint doesn't hide imperfections, it highlights them. Every layer line, blob, and seam that you skip during sanding will show through your paint job. Start here and invest the time.

For FDM prints (PLA, PETG, ABS):

• Start with 120-grit sandpaper to knock down visible layer lines and remove support marks
• Move to 220-grit to smooth the surface further
• Finish with 400-grit for a surface ready to accept primer
• For display pieces, continue to 600-grit and 800-grit for a glass-smooth finish

For resin prints: Resin surfaces are already smooth, so you mostly need to remove support nubs and seam lines. Start at 400-grit and finish at 800-grit. A quick rinse in soapy water after sanding removes dust and any remaining uncured resin.

Step 2: Filler Primer, Hiding What's Left

Even after thorough sanding, FDM prints will have micro-layer lines and small imperfections that sandpaper can't reach. Filler primer bridges these gaps. It's a thicker primer formulated to fill minor surface defects while providing a uniform base for paint.

Apply 2-3 light coats of filler primer (Rust-Oleum Filler Primer or Tamiya Surface Primer are both excellent), letting each coat dry for 15-20 minutes. Hold the can 8-10 inches from the surface and use smooth, sweeping passes. After the final coat dries fully (1 hour minimum), lightly sand with 600-grit to knock down any texture from the spray.

Step 3: Painting, Spray vs Brush

You have two main approaches, and the right one depends on the piece:

Spray Paint (Rattle Cans)

Spray paint is faster, more uniform, and better for large surfaces. Use automotive-grade spray paint for durability (Rust-Oleum 2X, Montana GOLD, or Tamiya for model work). Technique matters enormously:

• Apply 3-4 thin coats, not one thick coat. Thick coats run, drip, and obscure detail
• Wait 10-15 minutes between coats (touch-dry, not fully cured)
• Start and end each spray pass off the edge of the part, never reverse direction on the surface
• Rotate the piece between coats to catch every angle

Brush Painting (Acrylics)

Brush painting gives you precise control for details, color transitions, and small areas that spray can't reach. Use acrylic model paints (Citadel, Vallejo, or Army Painter are the standards in the miniature painting world). Thin your paints with water or acrylic medium until they flow off the brush smoothly, unthinned paint is too thick and leaves visible brush strokes.

The golden rule: two thin coats are always better than one thick coat. A thin coat dries quickly, stays smooth, and builds up color gradually. A thick coat pools in recesses, obscures detail, and takes forever to dry.

Step 4: Washes and Dry Brushing, Adding Depth

These two techniques transform a flat-colored print into something with visual depth and realism:

Washes: A wash is very thin, watered-down paint (or a dedicated wash product like Citadel Nuln Oil) that flows into recesses, crevices, and panel lines. It creates natural-looking shadows with zero effort. Apply it liberally over the painted surface, let it settle into the details, and wipe any excess off raised surfaces with a damp cloth.

Dry brushing: Load a small amount of lighter paint onto a brush, wipe most of it off on a paper towel, then lightly drag the almost-dry brush across raised edges. The paint catches only on high points, creating highlights. It's the opposite of a wash: washes darken recesses, dry brushing lightens edges.

Step 5: Clear Coat, Protection

A clear coat protects your paint job from scratches, UV fading, and handling wear. Choose your finish based on the look you want:

• Matte clear: Diffuses light, hides minor imperfections, looks realistic on props and models. Best for armor, weapons, stone, and organic surfaces
• Satin clear: Subtle sheen, good all-purpose choice. Works on almost everything
• Gloss clear: High shine, great for metallic finishes, automotive looks, and candy-coated effects. Shows every imperfection, so sand thoroughly beforehand

Apply 2-3 light coats of clear, just like primer. Let it cure fully (24 hours for spray-on polyurethane clears) before handling.

Material-Specific Notes

PLA: Accepts primer and paint well. Don't use solvent-heavy paints (lacquer, enamel thinners), they can warp or dissolve PLA. Stick to acrylics and standard spray paints.

PETG: Slightly more resistant to paint adhesion than PLA. Scuff with 220-grit before priming to ensure the primer grabs. Learn more about the differences in our PLA vs PETG comparison.

ABS: Paint-friendly. Can be vapor-smoothed before painting for best results. Solvent-based primers work fine on ABS.

Resin: Excellent paint surface out of the box. Make sure prints are fully UV-cured before painting. Uncured resin can cause paint adhesion failure and remains skin-irritating.

Painting 3D prints is equal parts patience and technique. The sanding and priming stages feel tedious, but they make the difference between a painted print and a professional-looking finished piece. Take your time with prep, keep your coats thin, and you'll be amazed at the results.