FCU Chassis Prototyping & Low-Volume Production
We partner with chassis designers & OEMs
Forerunner 3D Printing works with product designers, small OEMs, and accessory innovators to turn FCU chassis concepts into manufacturable, repeatable parts. We focus on FCU chassis prototyping fidelity, dimensional control, and small-batch production readiness.
Rapid Iteration
Fast turnaround on prototypes so you can validate fit and function with real FCUs.
End Use Material
Engineering-grade polymer Nylon 12, with post-process options for strength (Vapor Smoothing) & finish (Cerakote).
Repeatability
Process controls and dimensional verification to support prototypes and pre-production runs.
Platform Compatibility
We commonly prototype and produce chassis designed to accept the following fire control units (FCUs):
- SIG P320
- SIG P365
- Ruger RXM / RXM-FCI
- Springfield Echelon
- Other modern modular FCUs — contact us with your target unit if its not on this list.
We also prototype and produce rifle chassis as well that can accept actions like:
Capabilities & Processes
Forerunner 3DP specializes in producing FCU chassis prototypes and production-ready parts using HP Multi Jet Fusion (MJF) technology. MJF Nylon 12 delivers the combination of precision, surface finish, and mechanical performance that alternative 3D printing methods simply can’t match.
- Process: HP Multi Jet Fusion (MJF) — industrial-grade additive manufacturing with consistent isotropic strength.
- Material: PA 12 (Nylon 12) — excellent balance of stiffness, impact resistance, and heat deflection; ideal for structural chassis components.
- Dimensional consistency: ±.010″ typical on critical features; batch-to-batch repeatability.
- Surface finish: Smooth, uniform matte texture comparable to injection-molded polymer; optional bead-blast, dye, vapor smoothed, or Cerakote finish.
- Texture options: MJF parts allow complex surface textures—stippling, grip patterns, or branded geometries—to be printed directly into the part with no added cost or tooling. Surface textures are built layer-by-layer, eliminating secondary machining or mold engraving. Check out our dedicated page on the topic of textures on 3D Printed Parts.
- Thermal performance: Stable through extended firing-cycle heat loads; minimal creep/warping.
- Batch scalability: From single prototype to 500+-unit production batches.
- Cost efficiency vs SLS: HP MJF delivers faster cycle times, denser nesting, and lower per-part cost than traditional SLS printing — ideal for prototype-to-production chassis runs without tooling investment.
- Economics of complex geometry: Additive manufacturing is extremely cost-effective for complex, high-detail parts that would otherwise require expensive injection molds or 5-axis CNC machining. MJF Nylon 12 eliminates tooling costs while maintaining production-grade performance.
We exclusively recommend MJF Nylon 12 for functional firearm-chassis applications. Other additive methods (FDM, SLA, SLS) lack the mechanical strength and dimensional repeatability required for end-use components.
Why MJF Nylon 12 at Forerunner?
- Firearms and defense are a cornerstone of our business, we hold both FFL 07 and SOT 02 Licenses as well as a FEL.
- MJF Nylon 12 — the material of choice for structural polymer chassis.
- Our business is built on quality, we are ISO 9001 Certified and have an active quality management program.
- In house Cerakote application.
- NDA-friendly workflow — we protect confidential CAD and prototypes.
- Production-ready handoff: we can provide DFM reports and CAD feedback for scaling to injection molding when volumes increase.
Design-for-Manufacturability
If your chassis model needs refinement for MJF production — draft optimization, wall-thickness balancing, or tolerance stack evaluation — our DeWys Engineering team can help. Their firearm-experienced engineers adjust CAD models so critical features print flawlessly in MJF Nylon 12 and scale cleanly to tooling when you’re ready for molding.
Specifications & Fitment Guidance
These are the standard parameters we quote for MJF Nylon 12 FCU-chassis projects.
| Recommend Printing Process | HP Multi Jet Fusion (MJF) |
| Recommended Material | PA 12 (Nylon 12) |
| Layer Thickness | .003″ |
| Dimensional Tolerance | +/- .010″ for the first 1 inch, +/- .005″ per inch thereafter |
| Tensile Strength | ~48 MPa (ASTM D638) |
| Elongation at Break | 20 % (XY Plane) |
| Heat Deflection Temp | 95 °C @ 0.45 MPa |
| Surface Finish Options | Bead Blast, Dyed Black, Vapor Smoothed, Cerakoted |
| Minimum Batch Size | 1 Prototype → 500 + units |
| Inspection Deliverables (if requested / quoted) | First Article Inspection, % of each build inspected, Full Dimensional Layout with CMM |
Example Gallery
Typical Project Workflow
- Submit CAD model (STEP / X_T / STL) and identify target FCU platform.
- We review for MJF Nylon 12 manufacturability and advise on geometry adjustments if needed.
- Prototype build in MJF Nylon 12 — functional, test-ready parts. Typical lead time for this is 4-6 Days.
- Feedback / iteration cycle to lock geometry.
- Small-batch or pilot-production run with optional inspection report.
Most customers move from first print to validated chassis design in two to three cycles.
MJF Nylon 12 combines isotropic strength, high heat resistance, and fine surface finish, making it the ideal choice for functional firearm chassis that require repeatable accuracy and structural stability.
Typical dimensional control is ±.010″ on critical features. That precision is critical for FCU pocket and pin alignment.
We regularly produce chassis for the SIG P320, SIG P365, Ruger RXM, and Springfield Echelon platforms. Other modular FCUs can be accommodated as well.
Yes, but we do not use these technologies for FCU Chassis, Forerunner focuses exclusively on HP MJF Nylon 12 production for chassis applications, ensuring consistent mechanical properties, surface quality, and affordability of the end product.
Yes — we offer vapor smoothing, dye black, and Cerakote finishing upon request.
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