What Is the Strongest 3D Printing Material? A Complete Guide to Material Strength

Strength matters when you print functional parts including tools, jigs, fixtures, or anything that needs to withstand real loads. Strength, however, can mean different things to different people. When a part is described as “strong” it could mean in terms of holding a large load, resisting impacts and fractures, or resisting heat or environmental conditions.

In materials science, “strength” has a more narrow definition: it is the maximum amount of stress a part can withstand without breaking. “Stress” is the force applied divided by the cross-sectional area of the part to account for differences in geometry. Another important property related to the stress response of a material is stiffness. Stiffness is the amount of elongation or deflection caused by a given unit of stress. Strength and stiffness can be measured by pulling (tensile strength) or by bending (flexural strength). Strength and stiffness would be the most relevant properties for a load case where a part that needs to hold a heavy static load, like a bracket. Not all loads are static, and there are  other properties that characterize material performance under more dynamic load cases, like impacts.

When we talk about “toughness” for materials, we are describing the ability of a material to absorb energy and plastically deform without fracturing. There are a variety of ways to measure toughness. One way is to measure the energy absorbed from a hammer swung from a pendulum, or a falling weight, which is called “impact strength.” These measurements have units of energy (often J, J/m, or J/m2) unlike strength which is measured in force per area (usually in Pascals or PSI). Izod, Charpy, and Gardner are three popular styles of impact testing. Toughness can also be characterized in other ways like measuring the energy required to propagate a crack. Toughness is important when you want a part that needs to withstand extreme dynamic loads, like protective housing.

Before comparing 3D printing materials, it is important to establish what the mechanical properties used to measure strength mean. In 3D printing, "strength" is often a shorthand for a combination of the following mechanical properties: tensile strength, impact strength, flexural strength, heat deflection temperature (HDT), and stiffness.

Tensile strength measures the resistance of a material to failing under tension. It is the maximum stress a material can withstand while being stretched or pulled before failing. Imagine pulling a rope from both ends until it permanently deforms or snaps. The maximum force withstood divided by the cross sectional area is the ultimate tensile strength.

• Why it matters: High tensile strength is critical for parts that hang, carry static loads, or are pulled apart, such as lifting hooks or brackets.

• Measurement: Stress (Force per Area), usually in Megapascals (MPa)

Flexural strength is the material's resistance to failure under a bending load. This is usually tested with a three point bending test where a sample is supported by two posts and loaded in the middle. In bending, one surface is experiencing tensile forces as it tries to stretch apart, and the opposite surface is experiencing compressive forces as it is pushed together. Plastics typically have very good properties in compression and the flexural strength is usually higher than when loaded in pure tension.

• Why it matters: High flexural strength is critical for parts that must withstand bending forces like, beams, levers, cantilevered brackets, and frames.

• Measurement: Stress (Force per Area), usually in Megapascals (MPa)

Elastic modulus can be measured in tension or flex. 

• Why it matters: A stiff part (high modulus) will hold its shape under load, while a flexible part (low modulus) will deflect or stretch. For a drill locating jig, you would want a high modulus to ensure the hole location doesn’t shift under load. For a snap-fit enclosure, you want balance, with enough flex to snap, but enough stiffness to hold. 

• Measurement: Stress per unit of elongation – Usually GPa or MPa since elongation is treated as a ratio of initial length. Even though it shares units with strength, it is measuring stress per percentage of elongation – a material that has a modulus of 1000 MPa takes 10 MPa of stress to elongate 1% of its original length.

Impact strength measures a material's ability to absorb shock and sudden energy without breaking. A material with high tensile strength but low impact strength (like glass or standard PLA) is considered "brittle." If you need a part that can withstand drops or hits, look for high impact resistance. For Izod and Charpy impact resistance the samples may be either “unnotched” or “notched” where a small v-shaped notch is cut into the part. This notch acts as a starting point for crack propagation and makes the test much more challenging.

• Why it matters: Crucial for protective casings, drone parts, jigs, fixtures, tools, or items that might be dropped. 

• Measurement: Energy absorbed divided by the thickness or area of the test specimen (J/m) or kJ/m². For Gardner Impact Resistance, only energy is reported.

HDT is the temperature at which a polymer deforms under a specified load. HDT is the preferred way to compare the temperature at which load capacity diminishes. The glass transition temperature (Tg) is sometimes used as a proxy for HDT, and while this works well for amorphous thermoplastics like ABS, Tg  and HDT can  be very different from HDT for semicrystalline materials (Nylon, PP) and Thermosets like SLA Resins.

• Why it matters: "Strong" parts are useless if they warp in a hot car or inside an enclosure with electronics. This matters for parts in mechanical assemblies, machines, or parts used in hot environments.

• Measurement: Failure temperature in degrees Celsius (°C) at 0.45 MPa or 1.8 MPa of load.

FDM can produce strong parts, but they are anisotropic, and generally significantly weaker along the Z-axis.

FDM printers build parts by extruding melted plastic layer by layer. While the bond within a single layer (X and Y axes) is strong, the bond between layers (Z-axis) is significantly weaker, often by 30% to 50%.

SLA printers use a laser to cure liquid resin. This chemical process creates covalent bonds between each layer as it is formed. As a result, SLA parts are isotropic: they exhibit uniform strength in the X, Y, and Z axes.

Engineers have more design freedom with SLA than FDM. You can orient a part for optimal surface finish or print speed without worrying that a load applied from the "wrong" angle will cause delamination failure. With advanced engineering resins, SLA can outperform several FDM filaments in tensile strength and stiffness.

SLS printers use a high-power laser to sinter a thermoplastic powder. Like SLA, the sintering process creates nearly isotropic parts. The greatest advantage of SLS 3D printers is that they don’t require support structures for printing.

SLS 3D printing offers some of the strongest 3D printing materials, including a range of nylon powders.

While the materials are broken out into strongest, toughest, and heat resistant materials, Polycarbonate (PC) hits all these. 

Polycarbonate (PC) is the strongest consumer-grade material available before stepping up to expensive industrial polymers like PEEK and PEKK. It is the same material used in bulletproof glass and riot shields. In FDM printing, it offers a great step up in both heat resistance and impact strength compared to ABS and Nylon. It is a challenging material to print, and is often blended with other materials to make it easier to print which will also reduce strength performance.

• Pros: Extreme toughness (impact resistance), very high heat resistance, optical clarity (in specific translucent blends), and high tensile strength.

• Cons: Difficult to print (requires very high nozzle temps of ~270-310 °C), hygroscopic (absorbs moisture), and prone to severe warping and delamination without a heated enclosure.

• Tensile strength: High (60-70 MPa). It is stronger than Nylon and ABS, capable of bearing significant loads.

• Stiffness: Moderate (2-2.5 GPa) Similar to ABS, but not as stiff as PLA.

• Impact strength: Very high. PC is arguably the toughest non-flexible filament. It can take repeated heavy hammer blows without shattering.

• Heat resistance: Excellent. With an HDT of ~110-130 °C, it remains rigid in environments where PLA and ABS would soften.

• Best for: High-temp functional parts, automotive components (under the hood), electrical cases, and transparent durable covers.

Overall, if your 3D printer can handle the heat required for printing, Polycarbonate is the best choice for parts that need to be strong and heat-resistant.

Carbon Fiber Reinforced Filaments (CF-Nylon/CF-PETG)

Carbon fiber filaments are usually a base plastic (like nylon, PETG, or ABS) filled with chopped or milled carbon fibers. These fillers increase the stiffness of the material, but usually do not significantly improve the tensile strength unless using longer chopped fibers which can cause nozzle clogs. The addition of carbon fiber filler tends to reduce warping in materials like PC and Nylon. When fillers are added to amorphous materials like ABS, PC and PETG, the HDT leads to minimal improvements, while adding fillers to Nylon can lead to an HDT just below the processing temperature of the material. 

• Pros: Extreme stiffness (high modulus), high dimensional stability (resists warping better than the base material), lightweight, good surface finish.

• Cons: Abrasive (requires a hardened steel nozzle to print), expensive, and can be more brittle and harder to print than the unreinforced base material.

• Tensile strength: High (50-100+ MPa, depending on the base). Strength can be higher than the base with long fibers at a higher loading, but with small fibers the strength can decrease. 

• Stiffness: Extreme (3 - 6 GPa) the fibers prevent the plastic from stretching, significantly reducing deflection under load.

• Impact strength: Moderate to good. While strong, the added rigidity means it absorbs less energy than pure nylon before failing.

• Heat resistance: Excellent. The fibers help the part hold its shape under heat, often pushing the heat deflection temperature higher than the base plastic alone, and achieving 150–160 °C.

• Best for: Structural parts, drone frames, automotive components, jigs, and fixtures where stiffness is critical.

Carbon fiber filaments are overall the strongest 3D printer filament available for FDM, in terms of stiffness and structural rigidity.

PEEK (Polyetheretherketone)

PEEK belongs to the PAEK family of high-performance thermoplastics and is widely considered one of the strongest polymer materials. Often used in aerospace and medical implants, it serves as a legitimate lightweight replacement for metal.

• Pros: Extreme chemical resistance, biocompatible (safe for implants), superior strength-to-weight ratio, and fire-resistant

• Cons: Extremely expensive (often hundreds of dollars per kg), requires specialized industrial printers (nozzle temps ~400 °C or more, chamber temps ~100 °C or more), and difficult to process.

• Tensile strength: Extreme (90-100 MPa). PEEK approaches the strength of some aluminum alloys while being significantly lighter.

• Stiffness: Very high (3.5-4.5 GPa) PEEK is one of the stiffest unfilled polymers.

• Impact strength: High. It is incredibly tough and resists fatigue and stress-cracking well.

• Heat resistance: Superior. It can withstand continuous use at temperatures up to 260 °C (if annealed), making it suitable for engine parts and aerospace valves.

• Best for: Metal replacement, aerospace components, medical implants, and chemical processing equipment

All in all, PEEK is a high-performance industrial engineering material.

PEKK (Polyetherketoneketone)

PEKK is a close relative of PEEK but is often preferred in 3D printing because it is slightly easier to process. Its molecular structure allows for a slower crystallization rate, which reduces the internal stresses that cause warping during the printing process.

• Pros: Lower printing warping than PEEK, excellent layer adhesion, extreme chemical and heat resistance, low outgassing (crucial for space applications).

• Cons: Extremely expensive, requires high-temperature industrial hardware, requires annealing (baking) to unlock full thermal properties.

• Tensile strength: Very high (80-93 MPa). While sometimes slightly lower than PEEK in raw tension, it often exhibits better compression strength.

• Stiffness: High (2.5-4 GPa) slightly less stiff than PEEK, but still stiffer than most unfilled polymers.

• Impact strength: High. Like PEEK, it is durable and tough, suitable for harsh environments.

• Heat resistance: Superior. Similar to PEEK, it handles temperatures well over 150 °C, and up to ~250 °C or more after annealing.

• Best for: Aerospace parts (due to low outgassing), oil and gas components, and structural parts where PEEK warps too much. 

PEKK is often the strongest and most reliable alternative to PEEK when producing parts that might warp.

PLA (Polylactic Acid)

PLA is the default material for most FDM printers. It prints easily and produces stiff parts with good detail, but low overall durability.

It has a medium-to-high tensile strength (50–60 MPa), often higher than ABS or PETG. However, this strength is deceptive, since PLA is extremely brittle.

• Pros: High stiffness, easy to print, affordable.

• Cons: Very low impact resistance, low heat resistance (deforms around 50 °C), biodegradable (can degrade in UV/moisture).

• Strength: Ultimate Tensile Strength is  High (53 MPa). 

• Stiffness: High (2.5-3.5 GPa) PLA is very stiff and deflects less under load than ABS or PETG. 

• Toughness: Impact strength is very low, with a Notched Izod of 16 J/m. PLA is brittle; it shatters rather than bends when hit.

• Heat resistance: Low. PLA softens around ~55–60 °C, making it unusable for high-temp applications. PLA can often be annealed much like PEKK and PEEK to improve thermal properties by allowing for additional polymer crystallization to occur. PLA that has been heat treated this way will have a temperature resistance around 110 °C - 130 °C.

• Best for: Aesthetic models, non-load bearing prototypes, quick "looks-like" models.

Overall, PLA is good for rigid, static objects (like a pen holder), but too brittle for strong, functional mechanical parts.

PETG  (Polyethylene Terephthalate, Glycol-modified)

PETG is a modified version of the common PET material that is used to make water bottles and food packaging and has the number “1” as its recycling code. PETG has the polymer backbone modified to improve processability, which makes it suitable for applications like injection molding and 3D printing.

PETG is one of the most widely used 3D printing filaments. 

• Pros: Tougher than PLA while being much easier to print than ABS or Nylon.

• Cons: Can have “stringing” artifacts on prints. 

• Tensile strength: High – (45-55 MPa) Close to that of PLA.

• Stiffness: Moderate - High  (2.0 - 3.0 GPa) Stiffer than ABS and close to as stiff as PLA.

• Impact strength: Low to moderate; typically higher than PLA, but lower than ABS.

• Heat resistance: Low. Typically ~70 °C

PETG offers a general-purpose option that sits between PLA and ABS in terms of impact and temperature performance. 

ABS (Acrylonitrile Butadiene Styrene)

ABS is the industry standard for injection-molded consumer goods (like LEGO® bricks). In 3D printing, it offers a balanced strength profile. It has a lower tensile strength than PLA (~34-36 MPa) but significantly higher impact resistance and ductility.

• Pros: Yields before breaking (ductile), withstands temperatures up to ~85 °C, can be smoothed with acetone.

• Cons: Prone to warping during printing, emits carcinogenic fumes, lower raw tensile strength.

• Tensile strength: Lower than PLA, but sufficient for many plastic parts.

• Stiffness: Moderate. 

• Impact strength: Moderate. ABS can resist impact better than PLA, but tends to have poor layer adhesion, causing easier fractures in the Z-direction.

• Heat resistance: Moderate. It withstands temperatures up to ~85–95 °C.

• Best for: Durable consumer goods, enclosures, parts requiring heat resistance.

ABS is a common answer when asking what the strongest 3D printer filament for general-purpose use is, as it is a reliable choice for functional parts that need to survive a drop or a hot environment. But it emits fumes and can be difficult to print reliably on budget machines.

Nylon (Polyamide)

Nylon (Polyamide) is widely regarded as one of the toughest thermoplastics. Unlike PLA (which is stiff) or ABS (which is ductile), Nylon offers a unique combination of strength, flexibility, and resistance to wear.

Nylon is the material of choice for functional parts that need to withstand repetitive mechanical stress, friction, or fatigue without snapping. It is self-lubricating, making it ideal for gears and moving parts. Nylon properties vary significantly based on grade and many filaments are blends of different Nylons like PA6, PA12, and PA11.

• Pros: High impact resistance, low friction coefficient, excellent chemical resistance, and high fatigue resistance.

• Cons: Highly hygroscopic (absorbs moisture from the air rapidly, ruining prints), prone to warping, requires high printing temperatures. Nylon filaments are frequently filled with Carbon Fiber to reduce shrinkage and make the material easier to print.

• Tensile strength: High (40-80 MPa). This varies heavily based on both grade and moisture conditioning. Dry Nylon is stronger and stiffer, but moisture content will “plasticize” or soften the material.

• Stiffness: Moderate to low (1.5-2.0 GPa). Typically less stiff than ABS

• Impact strength: Good. Nylon can be tougher than ABS, depending on the grade and moisture content of the final part.

• Heat resistance: Very good. Depending on the specific blend (PA6, PA12), it generally handles temperatures up to 120 °C or higher.

• Best for: Gears, bearings, living hinges, snap-fits, and tooling handles.

Nylon is a great choice for durable, impact-resistant parts that need some flexibility. When asking what the strongest 3D printer filament for functional gears and hinges is, the answer is usually nylon.

Chopped or milled glass and carbon fiber are added to filament to increase temperature resistance, as well as stiffness. Polyetherimide (PEI) is one such material that falls into this category. Commonly known as Ultem® (a brand name), PEI filament is known for heat resistance, strength, and chemical stability.

Nylon 12 Powder

Nylon 12 Powder is the industry's gold standard for SLS. It offers a versatile balance of strength, stiffness, and detail, with very low moisture absorption. It is the easiest powder to print with, reliably producing parts with tight tolerances and complex geometries.

• Pros: Excellent dimensional accuracy, easy to print, balanced mechanical properties, and has a good refresh rate.

• Cons: Less ductile than Nylon 11 Powder. It is stiffer and will snap sooner if bent aggressively.

• Tensile strength: High (50 MPa). It offers excellent general-purpose structural strength suitable for most engineering tasks.

• Stiffness: Moderate (1.9 GPa)

• Impact strength: Moderate (32 J/m Notched Izod). While tough, it is significantly less impact-resistant than Nylon 11 Powder or Nylon 12 Tough Powder.

• Heat resistance: Excellent. It withstands temperatures up to 171 °C @ 0.45 MPa.

• Best for: High-detail prototypes, permanent jigs and fixtures, housings, and general end-use parts.

Overall, Nylon 12 Powder offers the best balance of printability and performance for general prototyping and production where extreme ductility isn't required.

Nylon 12 Tough Powder

Nylon 12 Tough Powder is a specialized formulation designed to offer improved ductility and toughness while providing the same versatility and easy workflow as standard Nylon 12. It is less brittle than standard Nylon 12 Powder and offers the best refresh rate in the industry (reusing up to 80% of old powder).

• Pros: High ductility (flexes without breaking), excellent dimensional accuracy (reduced warping), and very cost-effective due to low refresh rate.

• Cons: Lower tensile strength than standard Nylon 12 Powder. Lower heat resistance under heavy mechanical loads.

• Tensile strength: Moderate (42 MPa). While slightly weaker than standard Nylon 12 Powder (50 MPa), it makes up for this with flexibility.

• Stiffness: Low to Moderate (1.5 GPa)

• Impact strength: Good (60 J/m Notched Izod). It absorbs shock well and is ideal for parts that need to snap or bend.

• Heat resistance: Excellent. It withstands temperatures up to 161 °C @ 0.45 MPa, though it softens at lower temperatures under high loads (HDT @ 1.8 MPa is 46°C).

• Best for: Snap-fit enclosures, ratchets, hinges, functional prototypes, and long parts susceptible to warping.

Overall, Nylon 12 Tough Powder is the go-to powder for difficult geometries that tend to warp, or for parts that need more flexion than standard Nylon 12 Powder.

Nylon 12 GF Powder

Nylon 12 GF Powder is a glass-filled composite material designed for applications where stiffness and thermal stability are critical. By incorporating glass beads into the standard Nylon 12 base, this powder produces parts that are significantly stiffer and flatter than unreinforced nylon, making it ideal for maintaining structural rigidity under load or heat.

• Pros: High stiffness (high tensile modulus), excellent thermal stability (high HDT), and produces very flat parts with minimal warping.

• Cons: More brittle than unfilled Nylon 12; abrasive to post-processing equipment over time.

• Tensile strength: Moderate (38 MPa). While the raw tensile breaking point is slightly lower than pure Nylon 12, it resists stretching (deformation) much better.

• Stiffness: Moderate to high (2.8 GPa).

• Impact strength: Low to Moderate (23 J/m Notched Izod). The glass reinforcement adds rigidity at the cost of ductility, meaning it is more likely to snap than bend under sudden impact.

• Heat resistance: Excellent. It offers improved heat deflection compared to standard Nylon 12 (175 °C @ 0.45 MPa), maintaining its shape better in hot environments.

• Best for: Stiff housings, fixtures, tooling, threads, and parts requiring high sustained load-bearing capacity without creeping.

Overall, Nylon 12 GF Powder is the choice for stiff and stable parts. It is the go-to material when you need the printability of Nylon 12 but require increased rigidity.

Nylon 11 Powder

Nylon 11 Powder is a high-performance, bio-based material tailored for parts that need to bend and flex without snapping. While standard nylons are tough, Nylon 11 Powder offers superior ductility and impact resistance, making it the ideal choice for applications where the part might be dropped, twisted, or subjected to sudden shocks.

• Pros: Exceptional ductility (40% elongation at break), high impact strength, and excellent long-term stability. It is bio-based (derived from castor oil) and ideal for thin features.

• Cons: Can be more prone to warping than Nylon 12 Powder parts if not oriented correctly; printing in an inert nitrogen atmosphere is recommended for the best material properties and refresh rate.

• Tensile strength: High (49 MPa). It holds heavy loads well but is defined by its ability to stretch before failing.

• Stiffness: Low to moderate (1.6 GPa)

• Impact strength: Very high (71 J/m Notched Izod). It absorbs energy efficiently, making it one of the most shatter-resistant powders available.

• Heat resistance: Excellent. It has an HDT of 182 °C @ 0.45 MPa.

• Best for: Snap-fits, living hinges, orthotics, prosthetics, and thin-walled ducts that need to withstand abuse. 

Overall, Nylon 11 Powder is the specialist choice for durability and performance. If your part needs to survive real-world impacts or constant flexing, this is the material to use.

Nylon 11 CF Powder

Nylon 11 CF Powder is the strongest and most heat-resistant material in the Formlabs SLS material library. By reinforcing Nylon 11 Powder with carbon fiber, this material bridges the gap between plastic and metal. It offers the high impact resistance of Nylon 11 Powder combined with the extreme stiffness of carbon fiber, resulting in parts that are rigid, lightweight, and capable of handling repeated structural loading.

• Pros: Excellent strength-to-weight ratio, extreme stiffness (high modulus), and superior thermal stability.

• Cons: Requires printing with an inert nitrogen atmosphere; parts are rigid and will not yield much before breaking compared to unfilled nylon.

• Tensile strength: Very high (69 MPa). It is significantly stronger than standard nylons and resists deformation under heavy loads.

• Stiffness: Up to 5.3 GPa, but depends on part orientation since the fiber aligns with the X-axis. 

• Impact strength: High (74 J/m Notched Izod). Unlike many carbon-fiber filaments that become brittle, this powder retains the underlying toughness of Nylon 11 Powder, resisting shattering well.

• Heat resistance: Excellent. It has an HDT of ~188 °C @ 0.45 MPa, making it suitable for under-hood automotive applications and high-temp tooling.

• Best for: Metal replacement, high-impact equipment, aerodynamic components, and rigid jigs and fixtures.

Overall, Nylon 11 CF Powder is the top-tier choice for structural parts that need to be stiff, light, and heat-resistant all at once.

Depending on what strength means to your use case:

• Impact resistance (parts that will be dropped or hammered): Choose Tough 1000 Resin (SLA) for prototyping impact-resistant parts, and Nylon 11 Powder (SLS) for end-use impact-resistant parts. Tough 1000 Resin is chemically designed to absorb high-energy impacts. Nylon 11 Powder is the superior choice for ductility if you need parts like living hinges or orthotics that must bend repeatedly and stretch significantly without ever snapping. 

• Highest strength (load bearing): Choose CF-Nylon (FDM), Rigid 10K Resin (SLA), or Nylon 11 CF Powder (SLS). These offer the highest tensile strengths, making them strong enough to replace metal components in structural applications.

• Stiffness (parts that must not bend): Choose Rigid 10K Resin (SLA), CF-Nylon (FDM), or Nylon 12 GF Powder (SLS). Rigid 10K Resin provides glass-like stiffness (10 GPa modulus) for precision tooling, while Carbon Fiber reinforced Nylons (both FDM and SLS) offer extreme structural rigidity for lightweight functional parts.

• Heat resistance: Choose High Temp Resin (SLA), Rigid 10K Resin (SLA), or PEEK (FDM). For pure heat deflection (resisting deformation at ~238 °C), the SLA resins are superior. For continuous use in harsh chemical/hot environments, PEEK is the industrial standard. In SLS, Nylon 11 Powder and Nylon 12 GF Powder are excellent "mid-range" heat performers, handling ~170–180 °C, which is significantly higher than standard ABS or tough resins.

• Overall, balanced strength profile: Choose ABS/ASA (FDM), Tough 2000 Resin (SLA), or Nylon 12 Powder (SLS). These offer the best balance of performance and price.

  • FDM: ABS is the reliable, affordable standard for basic functional FDM prints.

  • SLA: Tough 2000 Resin is best for simulating ABS properties with a smooth surface finish.

  • SLS: Nylon 12 Powder is the gold standard for functional, end-use production parts that need to last.