What Is the Most Flexible 3D Printing Material?

3D printing isn’t just for hard plastics. It can also be used to produce flexible, rubber-like parts like grippy smartphone cases and medical devices. If you’re wondering what is the most flexible 3D printing material, this comprehensive guide will explore the top options. 

We’ll compare consumer-friendly materials like TPU and TPE filaments with advanced industrial elastomers used in SLA resin and SLS powder printing. Key technical specs like Shore hardness, elongation at break, and tensile strength will be detailed for each material. You’ll also learn real-world applications of flexible 3D prints in industries such as healthcare, automotive, robotics, and fashion. 

Finally, we’ll discuss the pros and cons (printability, durability, performance) of each material and provide recommendations to help you choose the best flexible material for your specific needs.

Understanding Flexible 3D Printing Materials and Their Properties

Tensile strength is an important attribute for flexible materials

Flexible 3D printing materials are plastics with rubber-like elasticity. In contrast to rigid thermoplastics, these materials can bend, stretch, and compress without breaking. Most flexible 3D printing materials fall under the category of thermoplastic elastomers (TPEs), which become pliable when heated for printing and solidify into a rubbery object when cooled. There are also specialized photopolymer resins and powders engineered for flexibility.

To compare flexibility, we need to look at a few technical specifications:

• Shore Hardness: This measures how soft or hard a material is on a durometer scale (typically Shore A for soft elastomers). Lower Shore A values mean a softer, more flexible material. For example, a 95A material is fairly firm (like a rubber shoe heel), whereas a 50A material is very soft (like a rubber band). Flexible 3D filaments usually range from about 60A up to 95A Shore hardness. Some new silicone-based resins can be as low as 40A Shore (extremely soft).

• Elongation at Break: This is the stretchability of a material, given as a percentage. It tells you how far the material can stretch before it breaks. Higher elongation means more stretchy. Many flexible 3D materials can stretch several times their original length. For instance, TPU filaments often have elongation between 300–600%, and some specialty filaments reach up to 950% elongation.

• Tensile Strength: The ultimate tensile strength is how much force the material can withstand while being stretched before breaking, measured in megapascals (MPa). While flexible materials are not used for their strength, it’s good to know if they can handle stresses. Some TPU filaments have surprisingly high tensile strength (on the order of 20–26 MPa), whereas very soft silicones or elastomers might have lower tensile strength (e.g., 3–9 MPa).

Understanding these properties helps in evaluating which material is “most flexible.” A “more flexible” material typically means lower Shore hardness and higher elongation, but you may trade off some tensile strength or ease of printing to get there. Next, let’s look at the common flexible materials for different 3D printing technologies.

Flexible Materials for Consumer 3D Printing (FDM & SLA)

In consumer-grade 3D printing, the two most accessible methods for flexible materials are FDM (Fused Deposition Modeling) using flexible filaments and vat photopolymerization processes—SLA (Stereolithography), DLP (digital light processing), and LCD—using flexible resin. Each has its own set of materials:

Flexible FDM Filaments

Flexible TPU filament

FDM printers can print flexible parts by using flexible 3D printing filament instead of rigid filament. To succeed with these flexible 3D printer filaments, use a slow print speed, ensure your printer is equipped for flexibles (a direct-drive extruder is highly recommended to avoid filament buckling in the feed path, and keep tension on the filament consistent. Bed adhesion is usually manageable: in fact, many TPU/TPE filaments stick well to build plates without a heated bed or glue (some, like Filaflex, don’t require special adhesives and still adhere strongly).

Avoid Bowden extruders for very soft filaments, as the long tube can cause the polymer filament to kink (the manufacturer of an ultra-soft 60A TPU explicitly does not recommend Bowden or all-metal hotends for their filament). Once dialed in, FDM flexible filaments let you create anything from custom phone cases and gaskets to drone bumpers or robot wheels at home. 

TPU

Thermoplastic Polyurethane is one of the most popular flexible filaments. It’s known for being durable, wear-resistant, and easier to print than some softer elastomers . TPU is slightly stiffer (often around 85–95A Shore), which actually helps with printability (less stringing and jamming). A well-known example is NinjaFlex TPU, which has a Shore hardness of ~85A and can stretch up to 660% of its length. TPU printed parts handle shock and wear well, making them great for prototypes of seals, grips, or even wearable items. 

Pros: Good durability (abrasion and UV resistance), decent strength (~26 MPa tensile for NinjaFlex ()), and relatively user-friendly for a flexible filament. 

Cons: Still more challenging to print than rigid filaments. Requires slower speeds, ideally a direct-drive extruder to prevent filament buckling, and careful tuning to avoid stringing. Also, standard TPU (85–95A), while flexible, may not be the absolute softest material available.

Recommended reading: What is TPU Filament in 3D Printing? Material Properties and Applications

TPE

Thermoplastic Elastomers are a broad category (TPU is technically a subset of TPE). Some products labeled TPE filament are extremely soft and elastic, even softer than TPU. These can have Shore hardness in the 70A–ninety-ish A range, with some at the lower end ~70A being very “rubbery.” TPE filaments can achieve very high elongation (reports of up to 900% in some formulations).

Pros: Super flexible and elastic: great for things like stretchable straps, bands, or phone cases that need to flex around an object. 

Cons: Difficult to print: the softer the filament, the more it tends to ooze, string, or jam. TPE often must be printedvery slowly and at lower temperatures to maintain shape. It may require trial and error to get good results, and often a printer with a direct drive extruder is a must. Printed parts can be very soft, but that can also mean less structural integrity (e.g., a very soft TPE part might tear under heavy load if not designed properly).

TPC

Thermoplastic Co-polyester is another type of elastomer filament, typically a bit stiffer (85–100A Shore range) and known for good chemical and heat resistance. It’s less common for hobbyists but used for parts that need to handle higher temperatures or chemicals.

Pros: More heat-resistant and often tougher against chemicals; still flexible but tends to be on the higher end of hardness (closer to a hard rubber).

Cons: Less flexible than TPU/TPE, and still requires careful printing (needs higher print temperature of ~230 °C and conditioned filament).

TPA

Thermoplastic Polyamide is essentially a blend of nylon with elastomer, yielding a smooth, highly flexible filament around ~80A Shore. It’s designed for parts that need to bend and twist repeatedly with durability.

Pros: Very durable and resilient; can handle repeated bending without cracking, ideal for wearables or hinges.

Cons: Like other ultra-flexibles, can be tricky to feed and print; availability is more limited than TPU/TPE.

Soft PLA

This is a modified PLA that is somewhat flexible (usually around 90A Shore hardness). It’s not as stretchy as TPU/TPE, but it can bend and offers better impact resistance than normal PLA.

Pros: Easy to print (similar settings to normal PLA in many cases) and holds its shape under light force but flexes under pressure.

Cons: Much less elastic than TPU: it behaves more like a stiff rubber that can flex but is not very “stretchy.” It can also be prone to extruder jams if not tuned, despite being PLA-based.

Flexible Resins for SLA 3D Printing

Bottle made from flexible resin (image: Formlabs)

SLA 3D printers use liquid resin, cured by a light source, and there are flexible photopolymer resins that produce rubbery parts. These materials are often proprietary formulations (each printer manufacturer has their own), but common options include Flexible Resin (around 80A Shore) and Elastic or Silicone-like Resin (around 50A Shore or even lower).

Why Choose SLA for Flexible Parts? SLA flexible materials have some advantages over FDM: the parts are fully dense and isotropic, meaning no risk of layer delamination under stress.[1] They also tend to be watertight and airtight, useful for things like custom gaskets or tubing that FDM might struggle with. The surface finish is smooth, and fine details (like texture or tiny features on a wearable device) are well-resolved. However, SLA printed elastomers might not have the same ruggedness against abrasion as an FDM TPU part: they are generally a bit more prone to tearing if stretched far beyond design, especially older resin formulas. Always check the resin’s data sheet for limitations like maximum strain.

Flexible 80A Resin

This is a resin with about 80A Shore hardness, similar to a flexible rubber or a TPU part. For example, Formlabs’ Flexible 80A resin has a Shore hardness of 80A, tensile strength ~8.9 MPa, and elongation at break ~120%. It’s considered a “soft-touch” material: flexible but with some rigidity. It works well for things like grips, handles, and seals that need to be somewhat firm yet have give. 

Pros: High detail and accuracy (since SLA can capture fine features), isotropic strength (no weak layers, the part is solid polymerized material in all directions), and good for functional prototypes requiring precise dimensions (e.g., gasket that must fit exactly).

Cons: The parts, being resin, can be sensitive to UV and heat: if left in sunlight or a hot car, they may degrade or deform over time. Also, flexible resins are usually a bit more expensive per liter than standard resins, and require proper support removal (which can be tricky since the parts are soft).

Elastic 50A (or 50–60A) Resin

These resins are formulated to be very soft and stretchy, akin to silicone rubber. For instance, Formlabs Elastic 50A resin has a Shore hardness ~50A (actually measured around 55A) and very high elongation (~160%). Parts made from such resin can bend and compress repeatedly without tearing, so they are great for simulating silicone parts like wearables (e.g., watch straps), compressible buttons, or soft robotic grippers

Pros: Extremely flexible (one of the softest materials available in desktop 3D printing) and high resilience: Elastic resin parts spring back to shape quickly and can handle many flex cycles. They can produce objects that feel like molded silicone.

Cons: Very soft resin parts have lower tensile strength (~3–4 MPa), meaning they won’t hold heavy loads: they are more for form-fitting or cushioning applications. Printing them can be a bit more challenging; the print must be carefully supported to hold its shape during printing and post-processing gently done to avoid deforming the soft part. Also, just like other resins, they can degrade with long UV exposure or certain chemicals.

100% Silicone Resin (40A)

A recent development is the ability to 3D print real silicone. For example, Formlabs’ Silicone 40A Resin produces parts at around 40A Shore hardness (very soft) and can stretch to about 230% elongation. Because the final material is chemically a silicone elastomer, such parts have excellent tear resistance (around 12 kN/m) and thermal stability, similar to molded silicone.

Pros: Highly durable elastomer (silicone) with real-world performance: resistant to heat and chemicals, and biocompatible for medical uses (meets ISO 10993 for short-term skin contact).

Cons: Currently, this requires specific resin formulations and compatible printers (e.g., Formlabs Form 3/4 with that resin). The parts still need UV post-cure and careful handling. This is more of an industrial/professional material due to cost and handling, but it represents one of the most flexible outputs you can get in 3D printing.

Industrial-Grade Flexible 3D Printing Materials

Beyond desktop printers, the industrial side of 3D printing offers even more options for flexible materials, often with higher performance or for production use. Two key technologies here are Selective Laser Sintering (SLS) and Multi-material inkjet processes (e.g., PolyJet) or advanced SLA/DLP like Carbon DLS.

SLS Elastomer Powders (TPU and Nylon)

Flexible PA11 SLS powder (image: Sinterit)

SLS 3D printing uses a laser to sinter powder into solid objects. It’s a popular industrial method because it requires no support structures and can produce tough, complex parts. Traditionally, SLS materials were mostly nylon (polyamide) which is semi-flexible when thin. But now there are purpose-made flexible powders:

TPU

Similar chemistry to TPU filament but in powder form for sintering. For example, TPU 90A powder is available for SLS printers (like Formlabs Fuse series). It produces fully rubber-like parts around 90A Shore hardness. Typical properties of SLS TPU are ~88–90A hardness, ~8 MPa tensile strength, and 250–300% elongation. SLS TPU parts have good elasticity and shock absorption, comparable to injection molded TPU parts. 

Pros: Production-quality parts: SLS can make functional final parts like custom seals, gaskets, bellows, or footwear components with consistent quality. The parts are usually strong and flexible in all directions (slightly anisotropic but much less than FDM) and have a nice smooth, matte surface. They can also be complex geometries (e.g., lattice structures for shoe soles) that would be hard to mold. 

Cons: SLS machines are industrial equipment, not common on a hobbyist’s desk. However, many service bureaus offer SLS TPU printing. Surface finish, while generally good, is a bit grainy from the powder; if you need a very smooth rubber surface, some post-processing might be needed. Also, SLS parts can exhibit a bit of variability in mechanical properties depending on orientation.

PA11

Nylon 11 is a polyamide that is more ductile and flexible than the more common Nylon 12. Some SLS Nylon 11 powders are formulated to be slightly flexible, suitable for hinges or living springs in designs. While Nylon 11 is not an elastomer (it won’t stretch like rubber), it can absorb impact and bend more without breaking compared to rigid plastics. It’s mentioned as a powder that “can be designed for flexibility” in SLS.

Pros: Tough and durable, with decent flexibility for thin-walled or lattice structures (often used in prosthetics and sporting goods that need some give). 

Cons: Not “rubbery” to the touch; more like a very tough plastic. If true elastomeric behavior is needed, TPU is preferred.

Other Industrial Flexible Materials: PolyJet & Digital Light Synthesis

Stratasys Tango flexible PolyJet material (image: Stratasys)

PolyJet Elastomers

PolyJet (from Stratasys) is a 3D printing tech that jets tiny droplets of resin and cures them, capable of multi-material printing. They offer rubber-like materials such as Agilus30 or formerly Tango series, with Shore hardness around 30A–60A. These allow printing of flexible parts or even combining flexible and rigid in one print (for overmolds, etc.).

Pros: Highest detail and multi-material capability: you can have gradient materials (mixing rigid and soft) and very intricate designs. Great for concept models of consumer products (like a razor handle with rubber grip, printed in one go).

Cons: PolyJet materials, while flexible, tend to be less durable in the long run: they can degrade (become sticky or tear) after months or years, especially with exposure to light/heat. Also, the printers are expensive and usually used by design firms or service bureaus, not individual makers.

Carbon DLS Elastomers (PU and Silicone)

Carbon’s Digital Light Synthesis (DLS) is a proprietary resin-based process. The company offers materials like EPU 40 (Elastomeric Polyurethane) and SIL 30. EPU 40 has about Shore 70A hardness, ~400% elongation, and 19 MPa tensile strength. It is a very high-performance elastomer used in applications like Adidas 4D shoe midsoles.[2] Carbon’s SIL 30 is a silicone urethane material around Shore 35A and 350% elongation, one of the softest 3D printed materials available.

Pros: Production-grade elastomers with properties approaching or matching molded parts; parts are isotropic and often end-use quality.

Cons: Access is limited to those with Carbon’s subscription-based printers or through service providers.

Direct Silicone Printing

Apart from Formlabs’ approach with resin, companies have tried to develop direct silicone 3D printers that extrude or jet real silicone. These can produce parts in the Shore 20A–60A range, fully comparable to molded silicone.

Pros: Real silicone with all its benefits (biocompatibility, high flexibility). 

Cons: Very specialized equipment, typically used in medical or aerospace industries for custom parts. Exciting silicone printing company ACEO (Wacker) ceased operations in 2021.

Recommended reading: Can You 3D Print Silicone?

Applications of Flexible 3D Printing Materials

Prosthetics and orthotics are a medical application of flexible 3D printing

One of the exciting aspects of flexible 3D materials is the diverse range of applications. From medical devices to fashion accessories, these materials enable innovations where a bit of stretch or bend is crucial. Here are some key industries and how they leverage flexible 3D printing:

Healthcare and Medical

• Prosthetics and Orthotics: Flexible filaments allow for printing prosthetic limb sockets or finger prosthetics that have give and comfort for the wearer. For example, flexible 3D printed prosthetic liners or grips can conform to a patient’s body, improving comfort. Orthotic insoles or braces can be custom-printed in TPU to provide support as well as flexibility where needed.

• Medical Models and Simulators: Surgeons use flexible resins to print realistic organ models (like heart or vascular structures) that can be cut or sutured for practice. Materials like Elastic resin can mimic soft tissue for surgical guides that bend or for training models of blood vessels. Patient-specific models (e.g., a model of a tumor in soft tissue) can be produced to feel similar to the real thing, aiding in pre-surgical planning.

• Wearable Medical Devices: Biocompatible flexible materials are used for devices that contact skin. For instance, custom 3D-printed splints, casts, or even prosthetic liners use TPU or similar for a comfortable fit. The flexibility ensures the device can move with the patient or be put on/removed more easily compared to a completely rigid device.

(In medical applications, always ensure the material is certified for biocompatibility if it will contact the body. Some 3D printed elastomers like certain Formlabs resins are ISO 10993 certified for skin contact.)

Automotive and Engineering

• Seals, Gaskets, and Hoses: The automotive industry often needs custom gaskets or seals for prototyping engines and enclosures. Flexible 3D printed seals (using TPU or flexible resin) can be made to fit complex shapes in engine bays. SLS-printed TPU gaskets can withstand the temperatures and pressures in functional testing. Similarly, flexible hoses or air ducts have been prototyped with TPU materials which can handle vibration and bending.

• Vibration Dampers and Bushings: Cars have many rubber bushings and mounts (for suspension, engines, etc.). Flexible materials allow making functional prototypes of bushings to test fit and performance. TPU’s high abrasion and tear resistance is beneficial here, and parts like shock absorbers covers or vibration isolators can be printed and evaluated quickly.

• Robotics and Drones: In robotic systems, flexible prints are used for robotic grippers, wheels, and bumpers. Soft robotic grippers, for instance, can be 3D printed in flexible filament rather than cast silicone. A case study used NinjaFlex TPU to create pneumatic robot gripper fingers that were quicker to iterate than molding silicone. In drones or electronics, TPU is popular for printing protective bumpers, camera mounts, and vibration dampening mounts, protecting components from shocks. In factory automation, end-of-arm tooling sometimes uses printed flexible pads or suction cups tailored to the product being handled.

Fashion and Wearables

• Footwear: 3D printing is making strides in footwear. Flexible materials like SLS TPU and Carbon’s elastomers have been used to produce shoe midsoles with complex lattice designs for optimal cushioning. A notable example is the Adidas Futurecraft series: early prototypes had midsoles laser sintered from TPU, making it “the first durable, fully flexible 3D printing material to be used in a consumer product.” These midsoles provide customized support and flexibility underfoot. Today, products like Adidas 4D shoes use Carbon’s DLS printed elastomers for a similar flexible lattice midsole. On the hobby side, people have even printed sandal soles or corrective shoe insoles with TPU filament.

• Clothing and Fashion Accessories: While printing an entire garment is tricky, designers have 3D printed dress components or textiles that incorporate flexible links. For instance, flexible filament can create chain-mail-like fabrics that drape. High-flex SLA resins have been used to print wearable art pieces that bend with the body. Fashion accessories like belts, wearable straps, or jewelry can benefit from flexible materials for comfort. Even something like a custom-fit watch band can be SLA printed in a flexible resin or FDM printed in TPU to perfectly fit your wrist.

• Wearable Tech: Flexible prints are useful for wearable gadgets like custom smartwatch straps, VR headset face pads, or flexible enclosures for electronics that need to be body-mounted. A flexible case can make electronics more ergonomic. The comfort and wearability of flexible materials is a big advantage in these applications.

Robotics and Soft Devices

• Soft Robotics: Soft robotics is an emerging field using squishy, compliant mechanisms. 3D printed elastomers are enabling new designs like inflatable actuators, grippers, and robotic joints without traditional hinges.[3] For example, researchers have printed entire soft grippers with internal air chambers that actuate when pressurized. TPU and flexible resins can also serve as elastic joints between rigid segments in a robot, granting it life-like motion. Because designs can be complex, 3D printing’s freedom is especially valuable here: you can create internal channels or complex geometries in a single print.

• Compliant Mechanisms: Beyond robots, any design that relies on material flexibility (living hinges, springs, etc.) can be directly printed. Nylon hinges are common, but for a truly elastic hinge, printing in TPU or a similar elastomer can yield a part that flexes thousands of times. Flexible couplings for motors (to absorb misalignment in shafts) are another example engineers have printed with TPU filaments.

In all these industries, flexible 3D printing materials unlock possibilities that standard rigid plastics can’t achieve. Whether it’s a prosthetic hand’s fingers bending naturally or a car’s custom seal printed overnight for testing, the ability to quickly fabricate rubber-like parts is a game changer.

Conclusion: Flexibility in 3D Printing Unlocked

Flexible 3D printing materials have opened up a world of possibilities where traditional rigid plastics fell short. From a hobbyist printing a custom phone case in TPU, to an automotive engineer prototyping a new rubber seal, to a fashion designer creating futuristic shoes with lattice midsoles, the ability to 3D print elastomeric parts is transformative.

We’ve seen that “the most flexible 3D printing material” can mean different things depending on context. For a consumer FDM user, it might be an ultra-soft TPU like Filaflex 60A (with 950% elongation). In an SLA lab, it could be a 50A Elastic resin or the new 40A Silicone that truly behaves like silicone rubber. In industrial production, it could be SLS or Carbon’s elastomers making end-use parts that combine flexibility with strength.

In practice, the “most flexible” material is the one that meets your flexibility needs while still being printable for you. Fortunately, as this guide shows, there’s a rich spectrum of materials to choose from. With some experimentation and the right material, you’ll be able to bend and stretch the capabilities of 3D printing — quite literally — to bring your innovative designs to life.

Frequently Asked Questions

What are flexible 3D printing materials?

Flexible materials, like TPU (thermoplastic polyurethane) and TPE (thermoplastic elastomer), offer rubber-like elasticity, making them ideal for shock absorption, gaskets, and wearable items.  

What are the challenges of printing with flexible filaments? 

Flexible filaments can be difficult to feed through Bowden extruders due to their softness, leading to jams or inconsistent extrusion. Printing at a slow speed and using a direct drive extruder improves results.

What technologies besides FDM/FFF can be used for flexible materials?

Vat photopolymerization technologies like SLA are compatible with flexible resins, while production technologies like SLS and PolyJet can also produce flexible parts.

How do flexible materials compare to rigid ones?

Unlike rigid materials like PLA or ABS, flexible filaments can stretch and bend without breaking. However, they typically have lower heat resistance and mechanical strength.

References

[1] Cosmi F, Dal Maso A. A mechanical characterization of SLA 3D-printed specimens for low-budget applications. Materials Today: Proceedings. 2020 Jan 1;32:194-201.

[2] Kajtaz M, Subic A, Brandt M, Leary M. Three-dimensional printing of sports equipment. InMaterials in Sports Equipment 2019 Jan 1 (pp. 161-198). Woodhead Publishing.

[3] Goh GD, Goh GL, Lyu Z, Ariffin MZ, Yeong WY, Lum GZ, Campolo D, Han BS, Wong HY. 3D printing of robotic soft grippers: toward smart actuation and sensing. Advanced Materials Technologies. 2022 Nov;7(11):2101672.