Ever wondered how custom LEGO parts are actually made? Not printed, not glued, but molded from real plastic like the pieces you grew up with? At BrickTactical, every custom LEGO gun, helmet and accessory starts as a design on a screen and ends as a solid ABS part that pops out of an injection mold we machined ourselves, right here in Washington. Here is how the whole process works.
What Is Injection Molding?
Injection molding is how nearly every plastic toy in the world is made. Plastic pellets are melted and forced under high pressure into a metal mold. The mold holds the exact shape of the part in reverse, down to the tiniest detail. The plastic cools in seconds, the mold opens, and a finished part is ejected. Then the machine does it again, and again, producing identical parts every time.
That is the big difference between injection molded custom LEGO parts and most other custom pieces on the market. A molded part is solid, smooth, strong and consistent. It clutches a minifigure hand the same way every time, and it will survive years of play.
Why ABS Plastic?
We mold our custom LEGO weapons and accessories in ABS, the same type of plastic classic building bricks are known for. ABS is tough, holds sharp detail, has a clean finish straight out of the mold and comes in a huge range of colors. It is the reason a BrickTactical rifle feels like it belongs in your collection instead of looking like an add on.
How We Make a Custom LEGO Part, Step by Step
1. Design
Every part starts in CAD. Founder Payton Dean designs each weapon or accessory in 3D, scaling real world gear down to minifigure size while keeping it compatible with minifigure hands, studs and clips. Getting the proportions right is half the battle: a part that is accurate but too thin will snap, and a part that is too chunky will look like a toy of a toy.
2. Prototype
Before we cut any metal, we print high resolution SLA 3D prototypes and test them on real minifigures. Does the grip fit the hand? Does the stock clear the torso? Does it look right in a squad of figures? Designs get refined here, sometimes for weeks or even months, until they are ready for a mold.
3. Mold Design
Next, the part is turned into a mold design. A LEGO mold, or any injection mold, is two halves that close together to form a hollow cavity in the shape of the part. The mold also needs a path for the plastic to flow in, vents to let air escape, and pins to push the finished part out. Designing all of that for a part smaller than your fingernail takes serious precision.
An aluminum injection mold for custom LEGO parts, machined in house.
4. Machining the Mold
Most of our molds are machined from aluminum on our own CNC mill. As Payton puts it, aluminum is "Strong, lightweight, and fast to machine! Not to mention a LOT cheaper than EDM cutting steel molds." That cost difference is what makes small batch custom LEGO parts possible at all. Even so, a single mold can take up to 48 hours of machine time, and a complex multi part mold like our M2 machine gun cost around $20,000 to build.
5. Testing
The finished mold goes into our injection molding machine for test shots. We check every detail: fill, fit, surface finish and clutch. If something is off, the mold gets adjusted and tested again until the parts come out crisp.
6. Production
Once the mold is dialed in, we run production in ABS, check the parts, pack them and ship them from Washington. That is it: a design that started on a screen is now a real custom LEGO gun in your minifigure's hands.
BrickTactical M2 parts in production.
Injection Molding vs 3D Printing Custom LEGO Parts
3D printing is fantastic for prototypes, and we use it every day in step 2. But for finished parts, injection molding wins:
- Strength. Molded ABS is solid all the way through. Printed parts are built in layers that can split or snap.
- Finish. Molded parts come out smooth with sharp detail. Prints often show layer lines or need sanding.
- Consistency. Every molded part is identical, so the thousandth rifle fits exactly like the first.
- Feel. Molded parts have the weight, color and clutch collectors expect from real building toys.
The tradeoff is up front cost. A 3D print costs almost nothing to start, while a mold costs thousands before the first part is made. That is why most custom parts you see online are printed, and why molded custom LEGO weapons are something special.
Can You Make Your Own Custom LEGO Pieces?
You can, and that is exactly how BrickTactical began. In 2012, at 12 years old, Payton and his grandfather bought a $2,000 desktop CNC mill and set out to make their own molds in the garage. "We didn't know what an endmill, CAD/CAM, or even a parallel was," Payton says. It took them about a year of phone calls to tooling reps and YouTube videos before they machined their first working mold. You can read the full story on our About Us page.
If you want to try it, start simple: learn CAD, 3D print your designs to test fit, and experiment with a small benchtop injection molder and an aluminum mold. Expect a learning curve. Or skip the curve entirely and shop parts we already perfected.
Payton with his first desktop CNC machine in 2013.
Frequently Asked Questions
How are LEGO pieces made?
Building toy pieces are injection molded: melted ABS plastic is injected into a precision metal mold, cooled and ejected. BrickTactical custom parts are made the same way, using molds we design and machine ourselves.
How much does a custom LEGO mold cost?
It depends on the size and complexity of the part. A simple single cavity aluminum mold costs far less than a steel production mold, while a complex multi part kit like our M2 machine gun cost around $20,000 in tooling.
Are BrickTactical parts 3D printed?
No. We use 3D printing only for prototypes. Every BrickTactical weapon and accessory you buy is injection molded ABS plastic, made in the USA.
Can BrickTactical mold my custom part?
We also offer custom printing and manufacturing services, including injection molds, CNC machined parts and prototypes. Reach out through our contact page with your idea.
Shop Injection Molded Custom LEGO Weapons
Every part in our catalog went through this process. Browse our custom LEGO guns and weapons, check out the BrickTactical M2 machine gun, or explore our custom minifigure accessories. And to see new molds as they come off the machine, subscribe to BrickTactical on YouTube.
