Onyx prototyping enables production-ready composite parts that combine the toughness of nylon with the stiffness of carbon fiber reinforcement. It is most similar to carbon fiber–filled nylon, but is designed for Markforged composite systems such as the FX10 and X7. Onyx is manufactured as a proprietary carbon fiber–filled nylon where the fibers are chopped extremely fine and consistently distributed. This allows it to be printed reliably through a 0.4 mm nozzle, enabling finer detail and smoother surface finish compared to many carbon fiber–filled filaments that require larger nozzle diameters.
The main consideration with using Onyx for prototyping is evaluating the performance advantages against the material cost. While standard nylons work well for many functional prototypes, Onyx excels when parts must maintain dimensional accuracy, deliver consistent surface finish, and withstand repeated mechanical use. It also serves as the base material for continuous fiber reinforcement, allowing parts to be strengthened with carbon fiber, fiberglass, or Kevlar when higher load-bearing performance is required.
This guide explains when to choose Onyx for your prototype, how it compares to other engineering plastics, and how to design parts that leverage its composite properties.
Onyx at a glance:
- Best for: Functional prototypes, jigs and fixtures, customer-facing parts, composite reinforcement base
- Print methods: FDM (Markforged printers only)
- Difficulty: Moderate
- Cost: $$-$$$
What is Onyx?
Onyx is a proprietary 3D printing material developed by Markforged. It is a micro carbon fiber–filled nylon that combines strength, stiffness, and heat resistance with a smooth surface finish. Onyx is commonly used to produce durable functional prototypes, tooling, jigs, fixtures, and end-use parts.
Onyx Explained: Material Properties That Matter for Prototyping
Onyx prototyping combines chopped carbon fiber reinforcement with an engineered nylon base to produce parts with higher stiffness and dimensional stability than standard thermoplastics. The carbon fiber increases rigidity and reduces warping, while the nylon matrix maintains toughness, chemical resistance, and impact durability.
This combination allows engineers to produce prototypes that function under real mechanical loads while maintaining a consistent, professional surface finish. In many cases, the same Onyx part can be used for both functional validation and presentation, reducing the need for separate cosmetic and mechanical prototypes.
Benefits of Using Onyx for Prototypes
- Consistent surface finish: Onyx prints with a uniform matte black appearance that typically requires little or no post-processing, making parts suitable for presentation and customer-facing prototypes.
- Dimensional stability: Chopped carbon fiber reinforcement improves stiffness and reduces shrinkage or warping, helping parts maintain tight tolerances and consistent fit within assemblies.
- Continuous fiber reinforcement capability: Onyx can serve as the base material for embedded continuous fibers such as carbon fiber, fiberglass, or Kevlar, enabling significantly higher strength and stiffness when required.
- Chemical and wear resistance: The nylon base provides resistance to oils, greases, and abrasion, making Onyx suitable for industrial environments and tooling applications.
Common Onyx Variants Used in Prototyping
Markforged offers specialized Onyx formulations for specific requirements:
- Onyx (Standard): Carbon fiber–filled nylon designed for general functional prototyping. It provides a balanced combination of stiffness, toughness, and dimensional stability for engineering parts.
- Onyx FR (Flame Retardant): Flame-retardant version of Onyx that meets UL 94 V-0 standards. It is commonly used in aerospace, automotive, and electronics applications where fire safety and regulatory compliance are required.
- Onyx ESD (Electrostatic Dissipative): Engineered to safely dissipate static electricity, making it suitable for electronics manufacturing, clean rooms, and environments handling sensitive components.
All Onyx variants can serve as the base material for continuous fiber reinforcement on compatible Markforged systems.
Key Onyx Properties to Consider
When designing prototypes with Onyx, several material properties influence how parts perform during testing and real-world use. The carbon fiber reinforcement increases stiffness and dimensional stability, while the nylon base maintains toughness and impact resistance.
Key properties that typically influence design decisions include tensile strength, flexural performance, thermal stability, and dimensional accuracy during printing.
- Tensile strength (40 MPa): Onyx provides sufficient strength for many functional prototype applications while maintaining toughness and impact resistance.
- Flexural strength (71 MPa): High bending resistance makes Onyx suitable for brackets, mounts, housings, and structural components that experience moderate loads.
- Heat deflection temperature (145°C): Onyx maintains structural integrity at elevated temperatures suitable for industrial environments and some automotive applications.
- Dimensional accuracy: The chopped carbon fiber reinforcement reduces shrinking and warping during printing, helping parts maintain tighter tolerances than many unreinforced thermoplastics.
Considerations for Onyx Prototyping
Onyx provides strong mechanical performance and surface quality but comes with several practical considerations.
- Proprietary system requirement: Onyx is designed for Markforged composite printers and cannot be printed on standard FDM systems.
- Higher material cost: Onyx is significantly more expensive than standard nylon or ABS, which can affect cost efficiency for large prototype runs.
- Abrasive material behavior: The chopped carbon fiber content can increase nozzle wear on printers not designed for abrasive materials.
- Best performance with reinforcement: Onyx is often used as the base material for continuous fiber reinforcement, allowing parts to achieve significantly higher stiffness and load capacity when required.
Tip: Use Onyx when parts benefit from its dimensional stability, surface finish, or reinforcement capability. For internal prototypes where appearance and stiffness are less critical, lower-cost engineering nylons may provide a more economical option.
Onyx is often selected when prototypes must serve both functional and presentation purposes. Engineering teams use it for parts that need to perform under real mechanical loads while maintaining a consistent appearance suitable for demonstrations, validation reviews, or customer presentations. When reinforced with continuous fibers, Onyx can also support load-bearing applications that would otherwise require metal components.
How Onyx Prototyping Works with Markforged
Onyx prototypes are produced using Markforged FDM (Fused Deposition Modeling) printers, which extrude carbon fiber–filled nylon filament through a heated nozzle to build parts layer by layer. While the process is similar to standard FDM printing, Markforged systems are designed specifically for composite materials, with hardened components and controlled extrusion systems that handle abrasive carbon fiber-filled filaments while maintaining consistent print quality.
A key capability of Markforged composite printers is the ability to embed continuous fiber reinforcement during the printing process. Printers equipped with this feature can place strands of carbon fiber, fiberglass, or Kevlar within the Onyx base material at specific layers and orientations. These fibers carry load in targeted directions, significantly increasing stiffness and strength compared to the base material alone.
This approach allows engineers to reinforce only the areas of a part that experience the greatest stress, creating lightweight composite structures that perform well in functional testing and tooling applications.
Onyx Prototyping Technology Comparison
Best Applications for Onyx Prototypes
Onyx is commonly used for prototypes that must combine functional performance with consistent surface quality. Manufacturing teams frequently use Onyx to produce jigs, fixtures, and tooling that must withstand repeated use while maintaining dimensional stability. Product development teams also use Onyx to create prototypes that can be tested internally and then presented to stakeholders without additional finishing.
Because Onyx can also serve as the base material for continuous fiber reinforcement, it is often selected for parts that may later require higher load capacity or metal replacement during development.
Common Onyx Prototyping Applications
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- Manufacturing tooling
- Jigs and fixtures for assembly processes
- Inspection gauges and go/no-go tools
- Custom soft jaws and workholding components
- Functional prototypes
- Housings and enclosures requiring dimensional accuracy
- Sensor mounts, brackets, and mechanical supports
- Components that must withstand moderate mechanical loads
- Customer-facing parts
- Design validation models for product reviews
- Demonstration parts and presentation prototypes
- Composite base for reinforcement
- Structural brackets reinforced with continuous carbon fiber
- Lightweight components requiring higher stiffness or metal-like strength
- Manufacturing tooling
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Onyx vs Related Materials
Getting Started with Onyx Prototyping
FAQ about 3D Printing Onyx for Prototypes
When should you use Onyx for 3D printing prototypes?
What is Markforged’s Onyx material?
Markforged’s Onyx is a proprietary carbon fiber–filled nylon used in composite 3D printing. It combines the toughness of nylon with increased stiffness and dimensional stability from finely chopped carbon fiber. It is designed for use on Markforged printers such as the Markforged X7 and Markforged FX10 to produce strong, functional parts with consistent surface finish.
When should you use Onyx for 3D printing prototypes?
Use Onyx when a prototype needs strength, stiffness, and dimensional accuracy beyond standard thermoplastics. It is commonly used for functional testing, tooling, and customer-facing parts. Systems like the Markforged printers are designed to print Onyx with consistent performance.
What industries use Onyx for 3D printing prototypes?
Manufacturing, aerospace, automotive, and industrial teams commonly use Onyx for tooling and functional prototypes. It is widely used for jigs, fixtures, and end-use parts that must withstand repeated mechanical stress. Many teams adopt Onyx on systems like the Markforged FX10 for production environments.
How much does Onyx cost for 3D printing prototypes?
Onyx is more expensive than standard nylon or ABS but less expensive than metal or continuous fiber composites. The cost is often justified by improved surface finish, dimensional stability, and reduced post-processing. It is typically used when standard materials cannot meet performance requirements.
What 3D printing methods are used for Onyx?
Onyx is printed using FDM technology on Markforged composite printers. Systems like the Markforged X7 and Markforged FX10 are designed specifically for carbon fiber–filled materials. These systems also support continuous fiber reinforcement for higher strength applications.
What is an alternative to Onyx for prototyping?
Alternatives include standard nylon or ABS for lower-cost functional prototypes and SLA or SLS materials for high-detail or durable parts. Systems like the Formlabs Form 4 are often used for visual models, while Formlabs Fuse 1+ 30W is used for durable nylon parts. These options are used when Onyx performance is not required.
