Materials for 3D Printing: Plastics, Metals, and More

The world of 3D printing has changed dramatically. It’s no longer just about making simple plastic models. Today, 3D printing creates real parts for demanding industrial uses. The secret to this success isn’t just better printers – it’s the growing selection of advanced materials. Understanding the full range of additive manufacturing materials is now essential for any engineer, designer, or manufacturing professional who wants to innovate. This evolution allows us to directly produce working end-use parts for the most challenging high-performance applications. New materials are driving this change, letting us create components that were previously impossible to make. This guide takes a detailed look at the main categories of plastics, metals, and composites, plus emerging options that are shaping the future of the industry.

Basic Building Blocks

To understand the complex world of 3D printing materials, we need to start with the basics. These are the most common material types that form the foundation of the industry. They give us a starting point before we explore more advanced and specialized options. This overview helps you navigate the vast materials landscape, providing important context for the plastics, metals, and ceramics that dominate today’s applications.

Basic vs. High-Performance Plastics

Plastic materials fall into two main groups. The first is basic plastics, which are perfect for early design testing. The second, high-performance plastics, offers better performance for more demanding jobs.

• Basic Plastics: Materials like PLA and ABS are the workhorses of concept modeling. They cost less and are easy to print, making them perfect for checking form and fit, visual aids, and non-working prototypes where appearance and basic shape are the main concerns.
• High-Performance Plastics: When a part needs to handle stress, materials like Nylon (PA), Polycarbonate (PC), and PETG come into play. They offer much better mechanical properties, temperature resistance, and durability, making them suitable for working prototypes, manufacturing aids like jigs and fixtures, and even small-batch production parts.

Common 3D Printing Metals

3D printing with metals has revolutionized how we make complex, high-value components. The most widely used metals serve as the industry’s backbone. Stainless Steel, particularly 316L, is valued for its excellent corrosion resistance and flexibility, making it a staple in medical devices and chemical processing equipment. Aluminum alloys like AlSi10Mg offer a fantastic strength-to-weight ratio, which is why they are heavily used in aerospace and automotive for making structural components lighter. Finally, Titanium alloys such as Ti-6Al-4V (Ti64) provide an unmatched combination of high strength, low weight, and superior biocompatibility, establishing them as the gold standard for medical implants and critical aerospace applications.

Specialized but Important Ceramics

While less common than plastics or metals, technical ceramics hold a critical position in 3D printing for applications where other materials fail. Materials like Alumina and Zirconia are defined by their extreme properties: exceptional hardness, very high-temperature resistance, chemical stability, and electrical insulation. These characteristics make them essential in specialized fields. 3D printing with ceramics enables the creation of complex cooling channels in electronic components, custom-fit, biocompatible dental and bone implants, and complex components for high-temperature fluid handling systems.

Basic Materials Overview

To provide a clear reference, the table below summarizes the general characteristics of these three foundational material categories.

High-Performance Plastics

As we move beyond basic materials, we enter the world of high-performance plastics capable of replacing metals in demanding environments. These materials are designed to withstand extreme temperatures, harsh chemicals, and significant mechanical stress, opening new possibilities for lightweight, high-strength parts in aerospace, medical, and industrial sectors.

The PAEK Family

At the top of the plastic performance pyramid sits the PAEK (Polyaryletherketone) family. This class of semi-crystalline thermoplastics is known for its extraordinary combination of thermal, mechanical, and chemical properties. Within this family, PEEK (Polyetheretherketone) and PEKK (Polyetheretherketoneketone) have emerged as the two most prominent and impactful additive manufacturing materials, enabling the production of parts that were once exclusively made from metals like aluminum and steel.

Deep Dive: PEEK

PEEK is often considered the benchmark for high-performance plastics in 3D printing. Its well-balanced and exceptional properties make it a go-to material for some of the most challenging applications.

Its qualities are best understood through a breakdown of its core properties.

• High-temperature resistance: PEEK maintains its mechanical properties at continuous service temperatures up to 250°C (482°F).
• Excellent mechanical strength and stiffness: It shows high tensile strength and a high modulus, rivaling some metals in specific strength (strength-to-weight ratio).
• Superior chemical and water resistance: It is virtually immune to degradation from a wide range of organic and inorganic chemicals, as well as hot water and steam.
• Natural flame resistance: PEEK carries a UL94 V-0 flammability rating without needing additives, producing very low smoke and toxic gas emissions.
• Biocompatibility: Medical grades of PEEK are available and widely used for implants due to their excellent biocompatibility and radiolucency (transparency to X-rays).

However, using these properties through 3D printing comes with challenges. PEEK requires very high processing temperatures, typically an extrusion temperature above 400°C and a build chamber heated to well over 100°C. This is necessary to ensure proper fusion between layers and to manage internal stresses, preventing warping and cracking. These requirements mean PEEK can only be printed on specialized, high-temperature industrial machines. Its key applications include metal-replacement aerospace components, custom surgical guides and long-term medical implants, and durable parts for chemical processing equipment.

Deep Dive: PEKK

PEKK is a close relative of PEEK within the PAEK family, but with a crucial difference in its chemical structure that gives it distinct processing advantages. While its ultimate performance characteristics are very similar to PEEK, its behavior during the printing process makes it a compelling alternative.

The primary difference between PEKK and PEEK lies in its processability. PEKK has a wider processing window and a slower, more controlled rate of crystallization. This is a significant advantage in 3D printing. The slower crystallization allows for better intermolecular diffusion between printed layers before the material solidifies, resulting in superior layer adhesion and, consequently, stronger Z-axis (interlayer) strength. This also helps reduce the buildup of internal stresses, making it less prone to warping, especially when printing large or geometrically complex parts. For this reason, PEKK is often considered easier to print than PEEK.

When should you choose PEKK? It becomes the superior choice in scenarios where part geometry is highly complex, featuring sharp corners or drastic changes in thickness. It is also preferred for applications demanding the absolute highest uniform performance, where that enhanced layer adhesion is critical to part integrity under multi-directional loads. While PEEK might have a slight edge in certain chemical resistance or steam sterilization cycles, PEKK’s processing advantages often make it the more practical choice for achieving reliable, high-performance parts.

For Extreme Environments

For applications that operate at the absolute limits of temperature and corrosion, even high-performance plastics and standard metals are insufficient. This is the domain of refractory metals. These materials are defined by their extreme resistance to heat and wear, and 3D printing is uniquely positioned to unlock their potential by forming them into complex geometries that are impossible to create with traditional methods.

What Are Refractory Metals?

Refractory metals are a class of metallic elements characterized by exceptionally high melting points, typically above 2000°C (3632°F), and extreme hardness at room and elevated temperatures. This group includes tantalum, tungsten, molybdenum, niobium, and rhenium. Their natural properties make them incredibly difficult and expensive to machine or form using conventional cutting techniques. 3D printing, particularly powder bed fusion processes like SLM and EBM, bypasses many of these challenges by building parts layer-by-layer directly from metal powder, enabling the creation of optimized, complex structures from these ultra-high-performance materials.

Material Spotlight: Tantalum (Ta)

Tantalum is a remarkable refractory metal highly valued in both medical and industrial sectors. Its processing via 3D printing has unlocked new applications where its unique combination of properties can be fully used.

• Key Properties: Tantalum’s defining feature is its outstanding corrosion resistance; it is immune to most acids below 150°C. It is also dense, flexible, has a high melting point of approximately 3017°C (5463°F), and is exceptionally biocompatible.
• Primary 3D Printing Applications: In the chemical industry, it’s used for reactor linings and heat exchangers that handle highly corrosive media. Its most transformative application, however, is in medicine. Using 3D printing, tantalum can be formed into porous, lattice-like structures for bone implants. These “trabecular metal” structures mimic the architecture of spongy bone, promoting excellent bone integration and long-term implant stability.

Material Spotlight: W & Mo

Tungsten (W) and Molybdenum (Mo) are two other critical refractory metals that are increasingly being utilized in 3D printing, often as pure metals or in alloyed forms.

• Tungsten (W): With a melting point of ~3422°C (6192°F), tungsten has the highest melting point of any metal on earth. This, combined with its incredible density and hardness, makes it ideal for extreme applications. In 3D printing, it is used to create radiation shielding for medical and nuclear applications, collimators for high-energy physics experiments, and even kinetic energy penetrators for defense. Printing pure tungsten is challenging due to its high thermal conductivity and tendency to crack, but ongoing process developments are making it increasingly viable.
• Molybdenum (Mo): Molybdenum has a lower melting point than tungsten at ~2623°C (4753°F) but offers an excellent balance of high-temperature strength and lower density. It serves as a high-temperature structural material. 3D printing applications include thruster nozzles for spacecraft, high-performance heat sinks for electronics, and electrodes for the glass-melting industry, where it must withstand extreme thermal cycling without degradation.

The Next Frontier

While plastics and metals form the core of the industry, the next frontier of performance is being defined by composites. Specifically, the integration of continuous fiber reinforcement into plastic parts represents a genuine paradigm shift, enabling the creation of components with the strength of metal at a fraction of the weight. This technology is moving 3D printing from a prototyping and tooling solution to a viable method for producing high-strength end-use parts.

What are 3D Printing Composites?

In the context of 3D printing, a composite is a material made up of a base plastic matrix (the “binder”) that is enhanced with a reinforcing material. The matrix, typically a durable engineering plastic like Nylon, provides the part’s shape and chemical resistance. The reinforcement, usually in the form of fibers, provides a dramatic boost in strength and stiffness. This combination creates a hybrid material with properties superior to either of its individual parts.

Chopped vs. Continuous Fiber

The critical distinction within 3D printing composites lies in the nature of the fiber reinforcement. This difference fundamentally changes the performance ceiling of the final part.

• Chopped Fiber Composites: In these materials, short fibers (typically carbon or glass, less than 1mm long) are pre-mixed into the base plastic to create a filled filament. When printed, these fibers are distributed randomly throughout the part. The benefit is a moderate, uniform increase in stiffness, strength, and heat deflection temperature compared to the unreinforced base plastic. However, the performance improvement is limited by the short length and random orientation of the fibers.
• Continuous Fiber Composites: This technology represents a completely different approach. During the printing process, a second print head lays down long, unbroken strands of continuous fiber—such as Carbon Fiber, Fiberglass, or Kevlar—directly into the thermoplastic matrix. The machine places these fibers precisely along critical load paths within the part. The benefit is a massive, directionally dependent increase in strength and stiffness. This is a paradigm shift in part performance, allowing a lightweight plastic part to achieve strength-to-weight ratios comparable to or even exceeding that of 6061 aluminum.

Applications of Continuous Fiber

The ability to strategically place strength only where it is needed unlocks unprecedented performance and design freedom. In our work, we’ve directly replaced machined aluminum jigs with continuous carbon fiber reinforced nylon parts, reducing component weight by over 75% and cutting lead times from weeks to days. The approach is to analyze the load paths in a component and use the software to reinforce those specific regions, creating a part that is both strong and maximally efficient.

• Manufacturing Aids: This is a primary application. Custom jigs, fixtures, and soft jaws for CMMs and CNC machines can be printed to be strong, lightweight, and non-marring to delicate parts.
• Robotics: End-of-arm tooling (EOAT) is a perfect use case. Lighter grippers and brackets allow a robotic arm to move faster, carry a heavier payload, or be downsized for cost and energy savings.
• Automotive: In motorsports and specialty vehicle development, continuous fiber is used for prototyping and low-volume production of brackets, mounting hardware, and even structural components where weight is a critical factor.
• Drones / UAVs: The demand for maximum rigidity and minimum weight makes continuous fiber ideal for creating drone frames, motor mounts, and other structural elements that improve flight time and payload capacity.

Sustainability & Future Horizons

As manufacturing evolves, sustainability is no longer an afterthought but a core consideration. 3D printing presents a unique opportunity to create a more responsible production ecosystem, driven by material innovation and process efficiency. Looking forward, the landscape of additive manufacturing materials is set to become even more dynamic and capable.

The Push for Greener 3D Printing

A significant push is underway to develop and adopt a wider range of sustainable 3D printing materials, addressing the entire lifecycle from sourcing to end-of-life.

• Recycled Materials: A growing number of filaments are now produced from recycled sources. This includes rPET, which is made from post-consumer plastic bottles, and filaments derived from recycled industrial plastic waste, giving a second life to materials that would otherwise end up in a landfill.
• Bio-Based Plastics: PLA remains the most prominent example of a bio-based plastic, derived from renewable resources like corn starch or sugarcane. Under the right conditions in an industrial composting facility, it can biodegrade. Emerging bio-plastics, such as PHA (Polyhydroxyalkanoate), offer similar benefits and in some cases can even biodegrade in marine environments.
• Metal Powder Recycling: In metal powder bed fusion processes, a significant portion of the powder in the build chamber is not sintered into the part. Reclaiming, sieving, and reusing this unsintered powder is standard practice. This process is critical for reducing material waste and significantly lowering the cost per part, making metal 3D printing more economically and environmentally sustainable.

On the Horizon

The pace of material innovation is accelerating, driven by advances in material science and artificial intelligence. The next few years will see the commercialization of materials that seem like science fiction today. We are on the cusp of widespread 4D printing, where parts are printed from smart materials that can change their shape or properties over time in response to an external stimulus like heat or moisture. The ability to print with multiple materials in a single part will become more sophisticated, allowing for the creation of components with both rigid and flexible sections or integrated conductive traces. Furthermore, AI-driven material discovery platforms are beginning to rapidly simulate and predict the properties of new alloys and plastics, drastically shortening the development cycle for the next generation of super-materials.

A Practical Guide

With such a vast and growing library of materials, the selection process can be daunting. However, by following a structured, application-driven approach, you can systematically navigate the options and identify the optimal material for your project. This framework turns technical knowledge into a confident, actionable decision.

Step 1: Define Requirements

The most critical step happens before you even look at a material datasheet. Material selection must begin with a deep understanding of the application’s functional needs. Forget about specific materials for a moment and ask these fundamental questions:

• Mechanical Needs: What loads will the part bear? Will it be under tension, compression, or shear? Does it need to withstand high impact or cyclic fatigue?
• Thermal Needs: What is the continuous operating temperature? Will it experience brief temperature spikes or extreme thermal shocks?
• Chemical Environment: Will the part be exposed to solvents, acids, bases, oils, or UV radiation?
• Regulatory Needs: Does the part need to be biocompatible for skin or implant contact, food-safe, or carry a specific flame-retardant certification (e.g., UL94 V-0)?
• Cost & Production Volume: Is this a one-off prototype where cost is secondary, or a low-volume production run where material and process cost are critical drivers?

Step 2: Use Databases

Once you have a clear list of requirements, you can use digital tools to dramatically streamline the selection process. Manually comparing datasheets for dozens of materials is inefficient and prone to error. Instead, use material selection software and databases. Tools like the Senvol Database, Granta MI, and software integrated directly into some 3D printing platforms (such as Markforged’s Eiger) allow you to input your specific property requirements—like a minimum tensile strength, a required heat deflection temperature, or chemical compatibility. The software then filters its extensive library to present you with a shortlist of candidate materials that meet your criteria, saving immense time and reducing the risk of overlooking a suitable option.

Step 3: Prototype, Test, Iterate

Theoretical selection is only the beginning. No datasheet can perfectly replicate the unique conditions of your specific application. The final and most crucial step is empirical validation. Once you have a top candidate material (or two), you must print and test. This can start with standardized test coupons (e.g., ASTM specimens) to verify key mechanical properties as-printed on your machine. However, the ultimate validation comes from printing a functional prototype and subjecting it to real-world or simulated real-world conditions. This iterative process of printing, testing, and refining the design or material choice is the only way to guarantee performance and reliability in a finished part.

Conclusion: The Material is the Design

As 3D printing solidifies its role as a mainstream production technology, the focus has expanded from geometric possibility to material capability. Material selection is no longer a final checkbox but an integral part of the design process itself, as critical as the CAD model. The ever-expanding palette of additive manufacturing materials, especially advanced options like continuous fiber composites, high-performance plastics, and refractory metals, is breaking down old barriers. This material-driven innovation is enabling a new generation of lighter, stronger, and more resilient products, fundamentally changing what is possible across aerospace, medicine, automotive, and countless other industries.