ETPU, or expanded thermoplastic polyurethane, is a specific type of 3D printer material that falls into the category of flexible filaments. Its base is the more familiar TPU material, which is a flexible rubber-like plastic. The attribute "expanded" means that the material has a foam or cellular structure. When it is manufactured, a gas is injected into the base plastic to create a large number of small, enclosed bubbles. This structure makes ETPU significantly lighter and softer than standard TPU. Its key feature is its shock-absorbing ability and high energy return, which means the material is very flexible and effectively returns to its original shape when compressed. In practice, this filament is used to print parts where low weight combined with softness and shock absorption are required. Typical applications include shoe midsoles and insoles, protective fillings for sports equipment, cushioning elements for machinery or soft, shock-absorbing handles.
