TPU (thermoplastic polyurethane) is a flexible, abrasion-resistant elastomer filament sold by Shore hardness, printable on standard FDM hardware and used for gaskets, grips, tires, and vibration dampers.
Hardness is the specification that governs everything else. TPU at 95A is stiff enough to feed like a rigid filament and is the practical starting point; 85A is noticeably softer and harder to print; anything below that requires a well-tuned direct-drive extruder. Bowden setups struggle across the range, because a flexible filament compresses inside the tube instead of advancing through it.
Printing runs at 210–230 °C with a 40–60 °C bed and unusually low speeds, typically 15–30 mm/s. The material is hygroscopic and should be dried before use. Retraction settings that work for rigid filaments produce jams and stringing, so profiles are rarely transferable.
Mechanically, TPU is chosen for compliance rather than strength. It absorbs impact by deforming and returning, resists abrasion and fatigue far better than rigid thermoplastics, and tolerates oils and fuels well enough that the polymer family is used commercially for fuel-line seals and gaskets — though prolonged immersion still causes gradual softening. No rigid material substitutes for it, because the property being purchased is elasticity itself. Comparative positioning lives in 📝3D Printing Filament Types.