Inside Our Sample Keychains: Design & Reliability Behind Markforged's Strength Showcase

Sample Part Background

At Markforged, we understand that customers need concrete evidence of our materials’ performance. While fiber‑reinforced parts can rival aluminum in strength, the best way to build confidence is by letting users feel the difference themselves. Our user‑friendly sample‑part request system delivers that proof directly to the customer’s doorstep. The most requested set is two keychains: the first crafted from plain Nylon, the second from Onyx infused with Continuous Carbon Fiber.

Meeting demand for these samples is a complex operation. In a high‑volume month, we ship 3,000 two‑piece sets—equivalent to 6,000 individual parts. Achieving this throughput required careful design decisions:

1. Material efficiency: Parts must be compact and use fiber sparingly so we don’t divert material from commercial orders.
2. Zero print failures: We batch print 24 parts per build to maximize printer uptime and minimize labor. A single failure would jeopardize the entire batch, so reliability is paramount.
3. Minimal post‑processing: At this volume, parts must be essentially ready for shipment straight from the build plate.

Even seemingly simple components like keychains demand thoughtful engineering. In the sections that follow, we walk through the design of each variant.

Nylon Keychain

The Nylon‑only keychain serves as a control. Although Nylon is no longer our primary base material, it represents the ductility of our most flexible resin in a standard build configuration. The part is translucent enough for observers to see its internal structure, which consists of a 50% triangular infill printed at 100 µm layer height. This layout provides strength while limiting weight and mitigating warping. The accompanying image illustrates the backlit print alongside an Eiger slice screenshot, clearly revealing the triangular membrane.

Even lettering on the keychain required verification. Because Nylon has slightly lower dimensional stability than Onyx, we manually adjusted the font to ensure consistent, accurate printing of each letter.

Onyx‑CCF Keychain

In contrast, the Onyx/Continuous Carbon Fiber keychain combines our strongest thermoplastic with premium fiber. However, material strength alone does not guarantee manufacturability. The initial design—maximizing fiber to demonstrate the difference—reduced print reliability and increased costs. To reconcile strength, reliability, and cost, we introduced two critical changes:

1. Switched the base resin from Nylon to Onyx, which is more compatible with fiber and yields higher print success rates.
2. Adopted a shelled fiber fill strategy. Instead of full fiber in every section, we use concentric full fill only on the top and bottom layers, and a single‑ring concentric fill in the middle layers. This approach preserves essential strength while dramatically reducing fiber usage.

The resulting part features three distinct fiber regions, and the accompanying cutaway image shows the exterior, interior, and Eiger slice for comparison.

By applying these design tactics, we achieve the reliability needed for large‑scale sample distribution while still showcasing the impressive performance of our materials.

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