Unlocking Flexibility: A Comprehensive Guide to 3D Printing Silicone

Lisa Ernst · 20.03.2026 · Technology · 15 min

The ability to craft intricate, flexible objects from silicone has revolutionized numerous industries, from medical devices to consumer goods. For years, engineers and designers grappled with the challenges of producing these soft, pliable components, often facing high costs and lengthy lead times. Now, innovations in 3D printing are dramatically shifting this landscape, offering unprecedented speed and design freedom.

Source: This image highlights the transformative impact of 3D printing on silicone part production, showcasing the intricate, flexible objects it can now create for diverse industries.

Quick Summary

Here’s a quick overview of what we will cover regarding 3D printing silicone:

• Direct Silicone 3D Printing: Recent advancements, especially with materials like Formlabs’ Silicone 40A Resin, allow for direct printing of 100% pure silicone parts with excellent flexibility and durability. This method is ideal for rapid prototyping and small-batch production.
• Silicone-like Materials: Various 3D printing technologies (FDM, SLA, SLS) offer materials with silicone-like properties, each with its own trade-offs in terms of precision, cost, and material characteristics.
• 3D-Printed Molds for Silicone Casting: A highly effective indirect method involves 3D printing molds, then casting real silicone into them. This approach is versatile, cost-effective, and allows for the use of various silicone types, making it suitable for a wide range of applications from prototypes to end-use parts.
• Key Considerations: Factors like Shore hardness, curing times, and mold design (one-part vs. two-part, vents, alignment features) are crucial for successful silicone part production.

Silicone Parts and the Evolution of Their Production

Producing soft or flexible parts in small batches often presents significant technical hurdles, proving both expensive and time-consuming. Silicone, a versatile synthetic rubber, can be configured for a vast array of applications, including seals, connectors, wearables, medical devices, robotic grippers, cooking utensils, and even thermal or electrical insulation. Traditional silicone production largely relies on established methods like injection molding, compression molding, or casting. While direct 3D printing of silicone does exist, its high viscosity historically made precise printing exceptionally difficult. Moreover, unlike photopolymers, silicone doesn't readily heat and extrude, nor does it typically cure with UV light.

The landscape of affordable silicone 3D printing solutions has only recently begun to emerge. For a long time, silicone 3D printers capable of working with 100% pure silicone were experimental and carried immense costs, often exceeding €100,000. However, 2023 marked a turning point when Formlabs introduced Silicone 40A Resin, the first truly accessible 3D printing material made from 100% pure silicone. This innovative material, based on Formlabs' Pure Silicone Technology™, seamlessly merges the desirable properties of cast silicone with the undeniable advantages of 3D printing. It enables the in-house production of pure silicone parts within hours, completely eliminating the need for traditional mold making and casting processes.

Direct Silicone 3D Printing with Formlabs

With Formlabs' specialized 3D printing solution, leveraging the Form 3B+ printer (starting from €3499), businesses can now manufacture 100% silicone parts internally. Parts printed with Silicone 40A Resin exhibit a Shore hardness of 40A, a tear elongation of 230%, and a tear strength of 12 kN/m. These robust characteristics make them ideally suited for applications demanding both flexibility and durability through repeated stretching, bending, and compression. Such 3D-printed parts also boast an impressive rebound resilience of 34% and maintain chemical and thermal resistance across a wide range, from -25°C to 125°C. Crucially, they can replicate fine details down to 0.3 mm, accommodating even the most complex geometries.

Direct silicone 3D printing with Silicone 40A Resin proves invaluable for rapid prototyping, creating manufacturing aids, tooling, small-batch production, and crafting custom, single-piece components. Its applications span from prototyping elastomeric consumer goods to automotive components and industrial accessories like connectors, grommets, actuators, keypads, and watch straps. This technology also facilitates the cost-effective production of limited quantities or unique end-use parts, such as custom seals. Examples include high-quality, durable custom manufacturing aids and tools, including flexible casting molds, fixtures, jigs, and masking aids. Medical device components, patient-specific prosthetics, and audiological applications also significantly benefit from this precise approach.

Companies are already actively leveraging these advancements. FINIS, for example, utilized 3D-printed silicone gaskets and buttons for functional prototypes of their smart swimming goggles. This allowed the FINIS team to print gaskets in just eight hours for €10 per piece, a stark contrast to the €1000 cost and three-week turnaround time for outsourced urethane casting. Dorman Products, an automotive parts manufacturer, employed silicone 3D printing for customized gaskets to effectively pressure-test new products. HGM Automotive Electronics even qualified 3D-printed components made from Silicone 40A Resin for end-use automotive applications following their rigorous internal testing.

Silicone-Like Materials and Alternatives

While direct silicone 3D printing offers distinct advantages, other 3D printing methods provide materials with appealing silicone-like properties.

FDM 3D Printing

Fused Deposition Modeling (FDM) offers thermoplastic polyurethanes (TPU) and thermoplastic elastomers (TPE) as flexible materials, with Shore hardnesses ranging from 45A to 90A. The primary advantages of FDM alternatives are the more affordable prices for both printers and materials. However, FDM typically suffers from lower precision, reduced dimensional accuracy, limited resolution, and generally lower part quality, strength, and design freedom. Silicone-like FDM materials usually possess less robustness than standard silicone, are not food-safe, have lower heat resistance, and offer fewer options for color and translucency.

SLA 3D Printing

Stereolithography (SLA) 3D printing provides high precision and a wide range of materials for silicone-like prototypes or end-use parts. SLA parts exhibit smooth surface finishes and greater design freedom than FDM. Silicone-like SLA resins are generally less robust than standard silicone, are not food-safe, and not typically biocompatible (though some may be skin-safe), and have lower thermal resistance. SLA materials can be translucent and colored, and are available with Shore hardnesses from 30A to 90A. Formlabs, for instance, offers Elastic 50A Resin, Flexible 80A Resin, and Rebound Resin as excellent silicone-like SLA material alternatives.

SLS 3D Printing

Selective Laser Sintering (SLS) is an additive manufacturing process commonly used in industrial applications, characterized by high accuracy and unrestricted design freedom. SLS materials with silicone-like properties include TPU, TPE, and TPA, with Shore hardnesses from 45A to 90A. Formlabs’ TPU 90A Powder is a particularly resilient elastomer suitable for durable products with high elongation at break and increased tear strength. This powder is widely used for flexible, skin-safe prototypes and end-use parts such as wearables, padding, dampeners, grippers, seals, soles, splints, orthoses, and prostheses. Parts produced with silicone-like SLS materials are dimensionally accurate, durable, abrasion- and wear-resistant, and offer the highest temperature resistance. Post-processing can render SLS parts biocompatible, skin-safe, and food-safe. Drawbacks of SLS include limited color and translucency options, and potential warping of thin-walled designs during cooling.

Creating Silicone Parts with 3D-Printed Molds

Another significant application of 3D printing involves creating rapid tooling for molding and casting silicone parts. This allows manufacturers to effectively bridge the gap between prototyping and mass production of silicone components.

The design process for molds begins in CAD software, where designers meticulously create molds suitable for compression molding, injection molding, overmolding, or even sacrificial molds. A suitable resin and an SLA 3D printer, such as those from Formlabs, are then used to precisely print the mold. After printing, the mold requires careful preparation for filling, which includes applying protective coatings and mold release agents. The desired silicone material is then prepared and poured into the mold. Upon demolding, the silicone part is meticulously trimmed and, if necessary, post-processed. This in-house rapid tooling facilitates the crucial validation of design and material choices before serial production and enables the efficient creation of customized end-use parts.

Companies like Google ATAP have utilized 3D-printed replicas to reduce costs by over $100,000 and shorten testing cycles from three weeks to a mere three days. Dame Products employs insert-molding with 3D-printed molds to beautifully encapsulate the internal hardware of beta prototypes in silicone. Psyonic uses silicone insert-molding for their prosthetic hand fingers, which consist of a rigid, 3D-printed core overmolded with silicone. Robotics manufacturers like RightHand Robotics employ the same process to produce grippers for their advanced robots. OXO, a renowned kitchen utensil manufacturer, uses 3D printing for prototyping rubber-like parts such as seals by utilizing 3D-printed dies for compression molding two-component silicone. The medical technology company Cosm manufactures patient-specific pessaries by printing molds on an SLA 3D printer and injecting biocompatible silicone. The production of custom otoplastics via 3D printing has revolutionized audiology, with far-reaching applications in hearing aids, hearing protection, and earbuds. Jaco Snyman of Dreamsmith Studios has also expertly used 3D-printed molds for his hyperrealistic silicone replicas and masks.

Source: property24.com

Jaco Snyman, pictured here, has effectively leveraged 3D-printed molds to create hyperrealistic silicone replicas and masks for Dreamsmith Studios.

Silicone is composed of polymers containing silicon chains that transform from a liquid to a rubber state through a chemical catalyst reaction. Room Temperature Vulcanizing (RTV) silicone rubber captures intricate surface details and, after curing, does not chemically adhere to 3D-printed molds. Mechanical bonds are, however, possible if silicone is poured onto porous surfaces. Liquid silicones are either two-component or one-component with a catalyst. Platinum-catalyzed silicones are more expensive but offer better long-term dimensional stability and low shrinkage, while tin-catalyzed silicones are more cost-effective but less durable and prone to greater shrinkage. The curing time for liquid silicones typically ranges from ten minutes to several hours. Silicone putty, a convenient two-component mixture, is hand-mixed, possesses a Shore hardness of 40A (similar to an eraser), cures in less than 20 minutes, and exhibits virtually no shrinkage. For safety and suitability, material safety data sheets must always be consulted to verify skin and mucous membrane compatibility, as well as food safety.

The Shore hardness of rubber-like materials is accurately measured on the Shore hardness scale A (for softer materials) or D (for harder materials).

Source: super-silicon.com

This detailed chart illustrates the Shore hardness scale, crucial for understanding the flexibility and rigidity of various materials like silicone.

Silicone resists heat and cold (from -65°C to 400°C), various chemical influences, and fungi. Silicone molds are inherently flexible, lightweight, and less prone to breakage or splintering, allowing for impressive elongation up to 700%. They can be reused for many cycles, with their lifespan depending on casting frequency and the inherent complexity of the design. However, silicone is generally more expensive than latex and organic rubbers and can tear if stretched with excessive force.

One-part silicone molds are perfectly suited for designs with a flat side and no deep undercuts. Two-part silicone molds are a better choice for reproducing complex 3D master models that lack a flat side or feature deep undercuts. Two-part molds intelligently divide into two halves that form a precise, fillable 3D cavity. Alignment features, such as cylindrical bumps, ensure correct and consistent alignment of the mold parts. Beveled pry points are also included to facilitate easy separation of the mold halves. The mold's parting line must be carefully considered during the design phase. When pouring silicone into the mold, it should be streamed from a sufficient height (at least 10 cm) directly into a corner of the cavity to minimize air bubbles. A mold release agent must be applied to all surfaces that are not intended to adhere to each other. Air bubbles in the silicone can be further minimized using a vibrating device or via careful, controlled stirring.

Two-component RTV molding systems (addition-curing) are particularly suitable for creating flexible parts. Pourable two-component silicone molding compound with a Shore hardness of A30 corresponds to a soft rubber. For helpful context, a Shore hardness of A10 is akin to gummy bears, A50-A70 is like car tires, and A100 is comparable to hard plastic. Silicone is virtually shrinkage-free and often food-safe, with a temperature resistance spanning from –50°C to 180°C (and short-term up to 250°C). Multi-part molds allow for clean demolding, as silicone is quite forgiving of draft angles and minor undercuts. The use of special release agents like release wax or PVA lacquer is often found to be unnecessary with silicone.

The components of the molding compound are precisely mixed by weight, where an electronic kitchen scale proves incredibly helpful. A good rule of thumb is that approximately 1.3 grams of mixed silicone yield a volume of 1 ml or 1 cm³. The prepared mixture is carefully poured into the mold and hardens according to the specific product, typically within a timeframe of a few minutes to 48 hours. Products with a pot life of about 30 minutes and a curing time of 24 hours are generally well-suited for many applications. Negative molds can be effectively sealed with painter's tape or power tape to prevent any leakage. For more complex, closed molds, vent channels (approximately 1 mm thick holes) must be strategically provided. Silicone is introduced through a central filling opening until it overflows from all vents. For smaller cross-sections, light pressure (e.g., applied with a syringe) can be beneficial without introducing additional air. After curing, excess material is meticulously removed with a sharp knife. Demolding is done carefully with a thin, flat screwdriver or the back of a knife. Sprues and vent channels are neatly removed with a sharp razor blade or side cutters. Any remaining imperfections can be smoothly removed with moistened fine sandpaper. The molded part can then be thoroughly washed with soap and water to remove residues. Molds can be reused multiple times; vent openings may need occasional cleaning, and a new mold release agent should be applied as needed. Iterating and refining mold designs is a common practice to adjust connection points, alignment pins, or vents for optimal results.

Overmolding is a sophisticated multi-stage molding process in which at least two components are molded over each other. A base component is initially created, and then another material is precisely molded over specific parts of it (e.g., plastic parts with integrated rubber grips). Mold making with silicone rubber is suitable for a diverse range of materials, including polyurethane, epoxy, polyester, plaster, concrete, cement, wax, low-melting alloys, or soap. Lukopren N Super is a two-part, condensation-curing silicone rubber that conveniently cures at room temperature in approximately 24 hours. The curing time is influenced by the amount of hardener used and the ambient temperature. The resulting mold is remarkably stable, chemically, and thermally resistant. Due to its excellent fluidity and low viscosity, a vacuum pump is not typically required. A high-quality master model is absolutely essential for achieving a quality cast. Overhangs in the model can potentially cause the master model or cast to get stuck in the mold, but silicone's inherent elasticity often helps prevent such issues. In the lost wax casting process, overhangs are not a concern at all, since the model is intentionally destroyed inside the mold. Any non-porous material, including 3D prints from filament or resin, is suitable for a master model in silicone rubber mold making. Print layers are visible on the final cast, so resin printing (e.g., with Original Prusa SL1) generally yields better results. Special casting resins designed for lost wax casting can be completely melted or burned out without residue. A 3D-printed template is often more dispensable and easily replaceable than a handmade one. Surface imperfections of the model will be accurately copied onto the final cast. An outer shell for the mold can be efficiently 3D-printed (e.g., with Original Prusa i3 MK3S). The entire interior of the shell, the surface of the modeling clay, and the master model must all be thoroughly covered with mold release agent.

Comparative Overview of Silicone 3D Printing Methods

To help you choose the best approach for your project, here's a comparative table of different silicone 3D printing methods:

Conclusion

The integration of 3D printing into the production of silicone components marks a significant and exciting advancement. Whether through direct silicone 3D printing or the strategic use of 3D-printed molds, manufacturers now possess more versatile, cost-effective, and rapid ways to create vital flexible parts. These cutting-edge technologies empower iterative design processes, facilitate custom manufacturing, and enable highly specialized applications, ultimately accelerating innovation across diverse industries, from innovative product design to high-precision medical devices. As material science and printing capabilities continue their relentless evolution, the possibilities for tailored silicone solutions will only continue to expand and impress.