3D Printing for Cosplay: Armor, Props, and Accessories

Cosplay has been transformed by 3D printing. What once required months of foam crafting, fiberglass molding, or expensive commissioned pieces can now be printed overnight. But printing is just the beginning—the real craft lies in finishing, assembling, and wearing your creation.

Here's what you actually need to know to go from STL file to convention floor.

Why 3D Printing Changed Cosplay

Traditional cosplay materials like EVA foam and Worbla require significant crafting skill. You're sculpting from scratch, building forms, heating and shaping by hand. The learning curve is steep.

3D printing flips this equation. The complex shaping happens in the digital file. Your job becomes finishing and assembly—skills that are easier to learn and more forgiving of mistakes. Sand too much? Print another piece. Mess up the paint? Strip it and start over.

The result: cosplayers can tackle more ambitious projects faster, with more consistent results.

Choosing the Right Material

Material selection can make or break a cosplay project. Here's what actually works:

PLA: The Starting Point

PLA is the most common choice for cosplay props, and for good reason. It's cheap, prints easily, and holds fine detail. For static props like swords, staffs, and display pieces, PLA works great.

But PLA has a critical weakness: heat. There are horror stories in the cosplay community of helmets left in cars that turned into puddles. Direct sunlight at outdoor conventions can cause warping. If your costume might see heat, PLA is risky.

Best for: Indoor conventions, handheld props, display pieces, detailed items where strength isn't critical.

PETG: The Durable Choice

PETG is what most serious cosplayers graduate to. It has a higher heat resistance than PLA—you won't lose your helmet to a hot car. It's also more impact-resistant, which matters for armor that might get bumped or dropped.

The tradeoff is printability. PETG tends to string more and requires dialed-in settings. It's also harder to sand, requiring more effort in post-processing.

Best for: Armor pieces, helmets, wearable items, anything that might see heat or impact.

Specialty Options

For large armor builds, lightweight PLA (LW-PLA) can cut weight by more than half. Full suits of armor get heavy fast—shaving weight matters when you're walking a convention floor for eight hours.

For props that need a specific look, specialty filaments offer interesting options. Wood-fill filaments create realistic textures for staffs and wands. Metal-fill filaments can be polished to a genuine metallic sheen for weapons and mechanical parts.

Print Settings That Matter

Cosplay prints have different requirements than functional parts or decorative items. Here's what to optimize:

Infill and Perimeters

For armor and wearable pieces, you want strength without excessive weight. A triangle infill pattern at 10-15% with 3-4 perimeters creates strong parts that can take impacts without being needlessly heavy.

Don't go too light on perimeters—you'll be sanding these parts extensively, and you don't want to sand through into the infill.

Layer Height

For armor and helmets, 0.2mm layer height is a good balance. Going finer adds print time without much benefit—you're going to sand and fill anyway. Going coarser means more work smoothing layer lines.

For highly detailed props with fine text or small features, drop to 0.12mm or 0.16mm in those areas.

Orientation

Print orientation is crucial for strength. Armor pieces should be oriented so layer lines run across stress points, not along them. A helmet printed standing upright is weaker than one printed at an angle where layers cross the stress areas.

The Finishing Process

Here's where the real work begins. Raw 3D prints look like 3D prints. Professional cosplay pieces look like they came from a movie set. The difference is finishing.

Sanding: The Foundation

Start with 180-200 grit sandpaper to remove the worst layer lines. Sand perpendicular to the layer lines—across them, not along them.

Work up through grits: 200, then 320, then 400. For a truly smooth finish, wet sand with 600 grit. Each grit removes the scratches from the previous one.

Critical tip: Raw PLA doesn't sand well. Apply filler primer first, then sand. The primer gives you a workable surface.

Filler Primer: Your Best Friend

Filler primer is a thick, sandable primer that fills minor imperfections. Rust-Oleum makes an excellent spray-can version. Apply a coat, let it dry, sand with 320 grit, repeat.

Two to three rounds of filler primer and sanding can eliminate visible layer lines entirely. This is the step that separates amateur prints from professional-looking props.

Filling Gaps and Seams

For larger gaps, seams between printed pieces, or damaged areas, you need actual filler. Bondo spot putty or 3M Acryl-Green are popular choices. Apply with a scrap of EVA foam—it acts like a squeegee and minimizes excess.

For structural seams on large pieces, some builders use a mixture of Bondo and fiberglass resin (called "rondo") brushed into the inside of joins for reinforcement.

Painting

Once your surface is smooth, painting is straightforward. Use a spray primer first—even if you used filler primer, a final coat of regular primer gives you a consistent base for paint.

Spray paint works excellently on properly prepared 3D prints. Metallic finishes look particularly good on the smooth surfaces.

For weathering, try painting a silver base coat under your main color. Once the top coat dries, gently sand the edges to reveal the "metal" underneath. This creates realistic wear patterns faster than any brush technique.

Don't forget: Always seal finished paint with a clear coat. Convention floors are rough on props.

Assembly Techniques

Most cosplay pieces are too large to print in one piece. A helmet might be eight separate sections. A full armor set could be dozens. Assembly matters.

Gluing Strategies

Super glue (CA glue) works fast but can leave white residue on surfaces. Use it for tacking pieces in position, not final assembly.

For permanent bonds on PLA, heat welding is superior. Use a soldering iron or wood-burning tool to literally melt the pieces together along the seam. Work from the inside so your finish surface stays clean.

PETG is harder to glue. Two-part plastic bonders or UV resin work well. Some builders use actual SLA resin and a UV flashlight for gap filling and bonding.

Alignment Tips

Dry-fit everything before gluing. Mark alignment points with a pencil.

Better yet: design alignment pins into your print. Small holes drilled through mating surfaces with brass pins glued in one side make assembly foolproof. You can't get it wrong when the pins only fit one way.

Reinforcement

For structural pieces like helmets, reinforce seams from the inside with additional material. Fiberglass resin, additional printed strips heat-welded in place, or even just generous amounts of epoxy along the seam lines.

Nothing ruins a convention faster than a helmet splitting along a seam.

Making It Wearable

A finished prop isn't finished until you can actually wear it comfortably.

Strapping Armor

3D printed mounting points are the cleanest solution for straps. Design small brackets with slots for nylon webbing, and print them right into your armor pieces.

For attachment, use at least two methods. Velcro alone can fail. Straps alone can shift. Combine them—velcro for quick attachment, straps for security.

Some builders use magnets embedded in armor pieces that match magnets in an undersuit. This looks cleanest but requires careful planning.

Padding Helmets

EVA foam or memory foam padding inside helmets serves two purposes: comfort and fit adjustment. Most printed helmets won't fit your head perfectly. Foam lets you customize the fit while making it wearable for hours.

Bicycle helmet padding kits work well and come pre-cut in useful shapes.

Weight Distribution

Full armor gets heavy. Distribute weight across your body using proper undersuit attachment points. Shoulder pieces should transfer weight to your shoulders, not hang from your neck. Leg armor should attach to a belt, not just strap to your thighs.

Plan this before printing. Adding attachment points later is harder than designing them in.

Getting Your Cosplay Printed

Not everyone has a printer large enough for cosplay pieces, or the time to dial in settings for large multi-day prints. That's where print services come in.

At Mandarin3D, we print cosplay pieces regularly. Our BambuLab printers handle both PLA and PETG with consistent quality—important when you're printing dozens of pieces that need to fit together. With our 250mm build volume, we can print larger sections with fewer seams.

If you have files ready to go, upload them directly and we'll quote the project. If you're still figuring out what's printable, reach out—we're happy to discuss material choices, print orientation, and how to get the best results from your files.

The convention floor is waiting. Let's get your costume printed.