We decided Zeta needed a new weapon for the lineup — or, more accurately, two new weapons.
For this project, we built a pair of Sangheili Curved Blades inspired by the Halo universe. From the beginning, this was more than a one-off prop build. We wanted these blades to become something we could offer as a kit in the shop, so the design had to work as both a finished convention prop and a repeatable build for other makers.
That meant thinking through the entire process: modeling, printing, assembly, internal reinforcement, surface prep, paint, and final finish.
This build log covers the full project, from the Fusion 360 modeling process and first print through the final chrome and graphite finish before San Diego Comic-Con.
Project at a Glance
Project: Sangheili Curved Blades
Build Type: 3D printed Halo-inspired prop weapon pair
Project Year: 2024
Built For: Zeta
Primary Goal: Create a finished pair of convention-ready curved blades while developing the process for future shop kits.
Modeling Software: Fusion 360
Printer: LulzBot TAZ Pro XT
Material: Polymaker PolyLite PETG
Assembly: Four internal dowel rods per blade, glue, and plastic welding staples
Recommended Adhesives: CA glue or 3DGloop
Surface Prep: XTC-3D, sanding, filler primer, Bondo spot putty, wet sanding
Finishing: Chrome paint with a full graphite rub for added depth
Final Debut: San Diego Comic-Con
Shop Intent: Kits planned for release after SDCC
Designing the Blades
The project started in Fusion 360.
The goal was to make Zeta a new weapon set: a pair of Sangheili Curved Blades. At this stage, the challenge was translating the in-game look into something that could actually be printed, assembled, finished, and eventually offered as a kit.
Once the model was where we wanted it, we moved into the first print to validate the shape and scale.
Designing the Blades in Fusion 360
Printing Two Blades
We did not just make one.
We printed two full curved blades and decided to document the entire project in a tutorial-style format. The idea was that once these were available in the shop, builders would have a clear idea of what the kit looked like and how the finishing process worked.
Fresh prints are always an exciting stage because the project finally moves from digital model to physical object.
At this point, we were checking the part breakdown, the printed surface, the overall proportions, and how the pieces would come together during assembly.
Assembly with Internal Dowel Rods
The curved blades were designed to integrate four internal dowel rods.
Those dowels serve two important purposes.
First, they make assembly easier by helping the blade sections align correctly. Second, they add strength through the body of the prop. For a long multi-part print like this, that internal structure matters.
Once the parts were aligned with the dowels, the sections could be bonded together with the builder’s adhesive of choice. For this type of assembly, we recommend CA glue or 3DGloop.
The dowel rods made the glue-up cleaner, straighter, and stronger.
Using internal dowel rods for assembly
Reinforcing the Seams
After the main sections were glued together, we added another layer of strength with plastic welding staples.
This is one of our favorite ways to reinforce multi-part printed props.
The process is simple: apply the staples across the seam, clip off the excess, and then use a Dremel to grind the area flat.
The staples create a mechanical reinforcement across the joint, which helps the finished prop handle sanding, finishing, transport, and normal convention handling.
For a blade this long, we did not want to rely only on adhesive. The combination of dowel rods, glue, and plastic welding staples created a much stronger assembly.
Applying Plastic Welding Staples
Applying XTC-3D
Once the blades were assembled and reinforced, we moved into surface finishing.
The first major step was applying XTC-3D from Smooth-On.
One useful tip when working with XTC-3D is to spread the mixed material out over a larger surface, such as an aluminum baking pan. That helps increase the working time before the material begins to cure.
From there, we applied the XTC-3D with a foam brush.
This helped seal the print surface and gave us a smoother base to work from during the next rounds of sanding and filler work.
Applying XTC-3D
Sanding After XTC-3D
After the XTC-3D cured, the blades had to be sanded.
For the broader surfaces, we used a small hand sander from Micro-Mark. For areas where the resin pooled or collected, we used a Dremel to clean things up more precisely.
That combination worked well because the blades had both large smooth areas and tighter spots that needed more control.
XTC-3D can do a lot to improve a printed surface while also adding a little strength, but it still requires sanding to get perfectly smooth.
Sanding XTC-3D with a sanding tool
Filler Primer, Bondo, and More Sanding
Once the XTC-3D was sanded, we applied filler primer.
Even with just filler primer, the blades already looked significantly cleaner.
Primer is also useful because it reveals problems. Small gaps, uneven areas, and surface flaws become much easier to see once everything is one consistent color.
After primer, we used Bondo spot putty to fill smaller gaps and imperfections.
Then came more sanding.
One important lesson from this stage is not to get too aggressive with the grit. If the sandpaper is too rough, it can remove the material you just added. For tight areas, sanding sticks are especially useful because they give more control than trying to force larger tools into small spaces.
Sanding Bondo and Filler
Wet Sanding and Chrome Paint
After a few rounds of filler primer and Bondo, we wet sanded the blades.
That final surface prep made a big difference before paint.
Then came the chrome finish.
This was the stage where the blades really transformed. After all the modeling, printing, assembly, reinforcement, coating, sanding, priming, filling, and wet sanding, the chrome paint finally gave the blades the bright metallic look we were aiming for.
Blades ready for chrome
Adding the Graphite Rub
One of the last finishing steps was a full graphite rub.
The effect is subtle, but it adds a lot.
Compared side by side, the blade with the graphite rub had more depth and a more realistic metallic look than chrome alone. The chrome finish gave the blades shine, but the graphite helped tone that finish and add visual character.
Graphite rub applied to Left blade in comparison to the Right blade that does not have graphite
Finished Curved Blades
With the graphite rub complete, the curved blades were finished and ready for San Diego Comic-Con.
In Halo lore, curveblades are Sangheili melee weapons historically used for hunting and close-quarters combat. That made them a perfect addition to Zeta’s Halo build lineup.
Two finished Curved Blades
What I Learned From the Curved Blades Build
This project was a good reminder that a successful prop kit starts long before the first coat of paint.
Design for assembly from the beginning.
The four internal dowel rods made the blade easier to align and much stronger once assembled. That kind of planning matters, especially on long multi-part props.
Use more than one reinforcement method when it makes sense.
Glue alone can work, but adding plastic welding staples gave the seams an additional mechanical bond. For a large prop that needs to survive handling and finishing, that extra strength is worth it.
XTC-3D helped smooth the print surface, but it still needed sanding. Filler primer helped reveal flaws, but it still needed Bondo and more sanding. Chrome paint looked good, but the graphite rub made it better.
Do not rush sanding.
The right grit matters. The right tools matter. A hand sander, Dremel, and sanding sticks all served different purposes on this build.
Zeta wielding her Curved Blades at SDCC
Final Thoughts
The Sangheili Curved Blades were a fun project because they combined design, fabrication, strength testing, finishing, and shop planning all in one build.
They started as a new weapon set for Zeta and became a tutorial-style project that helped define how we wanted the future kits to come together.
From Fusion 360 to the first print, from dowel rods and plastic welding staples to XTC-3D and graphite, every step had a purpose.
The finished blades were ready in time for SDCC, and the build gave us a clear process for turning them into kits for other makers.
Originally documented on the Alpha to Zeta Industries Instagram.
Want to Build Your Own?
We also offer raw 3D printed kits of our Sangheili Curved Blades in the shop.
These kits are designed for makers who want to take on the finishing process themselves, including assembly, sanding, priming, painting, and weathering. The build log above shows the same general process we used to finish our own pair, from internal dowel rod assembly through chrome paint and graphite finishing.
If you want to build your own set, you can find the Sangheili Curved Blade kit in our shop.
Have a custom prop or cosplay project in mind? Visit Custom Projects.