When you need to 3D print a part that bends, stretches, or absorbs impact, you generally have two options: Flexible UV Resin (for SLA/DLP/LCD printers) or Flexible Filament like TPU (for FDM printers). While both materials can produce rubber-like parts, they excel in entirely different applications.

At QTS USA, we manufacture premium grades of both flexible resins (ranging from an ultra-soft Shore 8A to a durable 68A) and specialty filaments. In this guide, we will break down the pros and cons of each technology to help you choose the right material for your next project.

1. Flexible Filament (TPU / TPE)

Thermoplastic Polyurethane (TPU) is the undisputed king of FDM flexible printing. It is widely used for drone bumpers, phone cases, and mechanical tires.

The Pros: TPU is incredibly durable. It boasts exceptional tear resistance and layer adhesion, meaning a well-printed TPU part is nearly impossible to pull apart by hand. It is also highly resistant to oils, greases, and many solvents.

The Cons: Printing TPU is notoriously difficult. It requires a direct-drive extruder, precise retraction settings to prevent stringing, and slow print speeds. Furthermore, FDM technology cannot produce smooth surfaces or intricate micro-details; layer lines will always be visible. Most TPU filaments are also limited to Shore 95A or 85A — anything softer becomes like trying to push a wet noodle through the extruder.

2. Flexible UV Resin

Flexible resins cure layer-by-layer under UV light, producing isotropic parts (equal strength in all directions) with completely smooth surfaces.

The Pros: Resin is unmatched for surface finish and high resolution. If you are printing wearable prototypes, custom earbud tips, or complex medical models, resin is the only way to achieve injection-mold-like quality. More importantly, resin can achieve softness levels that FDM simply cannot. For example, QTS Flexible 8A offers a silicone-like Shore 8A hardness with 700% elongation — impossible for FDM.

The Cons: Flexible resins require post-processing (washing and UV curing). If over-cured, they can lose their elasticity and become brittle over time. They also require careful support generation, as the soft material can warp under the suction forces of the FEP film during printing.

3. QTS USA Flexible Resin Lineup: A Shore Hardness for Every Need

If your project demands the high resolution and extreme softness of resin, QTS USA provides an industry-leading spectrum of flexible options, all manufactured in Taiwan and shipped from our US warehouse:

• QTS Flexible 8A ($47.99/500g): The softest resin on the market. Feels like human skin or soft silicone. Ideal for anatomical models and ultra-soft cushioning.
• QTS Flexible 25A ($47.99/500g): Rubber-like resilience with excellent tear resistance. Perfect for custom stamps and flexible seals.
• QTS Flexible 45A / 57A ($42.99/500g): The TPU equivalents in resin form. High impact resistance and tough rebound, ideal for footwear prototyping and functional hinges.
• QTS Flexible 68A ($47.99/500g): Heavy-duty industrial rubber. Built for high tensile strength and wear resistance in mechanical assemblies.