Cosplay

I have attended gaming culture conventions like PAX East and MAGFest for many years, and one of the highlights is seeing attendees dressed as their favorite characters. Cosplay is a fun way to show how much a piece of media means to you, connect with others who share your passion, and to develop many craft skills.

Past Costumes

My next project, currently in progress: B-01 Helldiver

Representation of finished cosplay by Galactic Armory.

I am a big fan of the narrative and gameplay of Arrowhead Studios' Helldivers 2, and witnessed many MAGFest 2025 attendees dressed as Helldivers. I feel I've achieved competency with my printers to the level where I can pull off producing a suit of armor for myself, with the goal of having it ready for MAGFest 2026 from Janurary 8th to 11th.

I use spreadsheets to track the progress of my pieces and identify where I need to be spending more of my time.

As part of this project, I am learning the tradeoffs and requirements of different plastics, as well as techniques for post-processing and painting 3D printed objects.

Material: PLA is known for easy printability, which reduces time spent on failed prints and testing settings. However, its low glass transition temperature of around 60°C means it can melt together rather than form particles when sanding. Filament vendor Polymaker sells a PLA variant called CosPLA specially designed to avoid fusing when subjected to sanding, which is what I decided to use for this project.
Fastening: While cutting large models into pieces, I discovered Prusaslicer's connector tools to add mechanical dowels for rebuilding the parts. I've picked up a can of 3D Gloop PLA solvent as well, which I heard from exhibitors at 3D Printopia was excellent for forming permanent bonds.
Post-processing: I have learned a process for removing the layer lines of prints, and the grits/primers/paints needed. Along the way I've picked up on relevant print settings to reduce the amount of work, such as reducing infill density while increasing number of perimeters, and using Prusaslicer's "Automatic Infill Combination" to set the infill's layer height as thicker than the perimeter height.

I discovered that the developers created a cosplay guide, which is a handy resource I wish I had known about sooner. Thanks Arrowhead!

Link to Official Cosplay Guide

Creating a Custom Tacpad

One challenge I have overcome is the tacpad worn on the wrist, which is hollowed out to hold a phone but lacks any means of securing it. I proved a concept to secure an old phone of mine, based on battery covers found on remotes and other devices. Using only the polygonal .stl file of the tacpad, I created a cover model with a compliant hinge to securely constrain the phone.

Concept sketches for tacpad mechanism.

Creating Interchangeable Nozzles

For safety reasons, prop guns are usually required to display a bright orange tip when brought to conventions, which includes MAGFest. Luckily, the nozzle that goes with the Liberator rifle I am working on is designed to be printed as a separate piece, which makes changing the color easy. However, the orange plastic I'm using is not PLA, so it won't bond using the PLA formulated 3D Gloop I have. I also would rather not create a permanent bond in case I want to change the nozzle for more realistic photos at a later date.

I was planning on using threads to mate the nozzle and front of the rifle together, but without the source model files for both parts it would be a hassle and require me to reprint the large front piece again. A friend suggested o-rings, which sounded like an elegant solution. I found a design guide at Global O-Ring and Seal, and created an Excel calculator quantifying performance characteristics along with ring dimensions. Using Excel's Solver add-in, I had the program find the optimal gland diameter given other dimensions of my model and a goal to set compression ratio to 0.2. A couple test prints later and I have something I can use!

The two mating parts, nozzle in orange.

Stock o-ring design process.

Excel calculator. Constants at top left, stock parts and performance characteristic on right. Design variations are described in the lower left table.

Modified nozzle cross section.

Printing:

Core One L printing the dome part of a helmet.

Core One L printing the body of a sample container.

Before printing in final material, I created fit checks in random plastics.

Back plate cut into pieces to fit on my MK4S. Dowel connector pins join the parts together.

Irregularly shaped part split for ease of printing. I use text embossing in the slicer to identify parts.

A whole slew of parts in progress.

Chest part split across seven beds. I printed this part before getting my Core One L, which would have reduced the number of splits needed.

One chest part sliced. From trial and error I learned to use supports not only for overhangs, but also for additional stability on upright parts.

Helmet front plate in progress on my MK4S.

Finished print job.

Calf guard printed as a single piece. The Core One L is ideal for jobs like this.

Some scale context for the job.

Helmet dome printed as a single piece. This is close to the limits of the Core One L's build volume.

Supports on the helmet interior.

All individual parts (minus tacpad) printed and laid out.

Box of parts.

Assembly:

Lower right plate of the back assembly clamped while glue cures.

I repurposed a clothes drying rack as a print curing rack with some flattened cardboard boxes.

All glued parts laid out. Some have been primed before gluing, which in hindsight is not a helpful step.

Back plate underside. Made of 11 parts.

Chest plate underside. Made of 7 parts.

Retouching:

Many of the seams left after the assembly process were oversized, so I used Apoxie Sculpt to fill any gaps between parts and cover up visible glue seams. The compound was surprisingly easy to work with, like handling firm Play-Doh or Sculpey modeling clay. It can also be smoothed with water before it cures which helps reduce the amount of sanding necessary.

Filling a gap between plates caused by the top part curling away from the bed during printing. The wooden skewer helped access tight spaces.

Filling detail seams in the right shoulder.

Front of chestplate before sanding.

Inside of chestplate before sanding.

Comparison of filler stages. Top to bottom: Overfilled, sanded with 60 grit, sanded with 400 grit.

Masking Contact Surfaces:

Some parts being glued to others differ in color. To keep mating surfaces clean and coarse I used masking tape to prevent them from picking up primer.

Overall masking guide I created highlighting contact surfaces.

Using an X-Acto knife to trim the mask.

Mask shown to right is the large rectangular vent piece.

Trimmed mask ready for priming. Surface beneath tape stays in better condition for gluing.

Creating Decals:

I have a Cricut vinyl cutter which I have used in years past to create layered stickers and other small art projects. I've been leveraged my skill in Inkscape, to create stencils of the decals for spray painting. I opted for paint over vinyl as vinyl may struggle to stick to a painted surface, would have a different surface texture/finish, and may not match the shades of white and yellow I use for the armor.