Military veterans and civilian amputees may soon benefit from a new type of prosthetic that helps them swim. According to the Congressional Research Service A Guide to U.S. Military Casualty Statistics, as of June 2015, there were 1,645 veterans with major limb amputations. Northwell Health estimates there are 1.9 million amputees in the U.S. and the number is projected to double by 2050.

Northwell Health’s medical technology development group, Northwell Ventures, has created “The Fin,” which is a 3D-printed, amphibious, prosthetic leg. The Fin enables amputees to navigate on land and in the water. The Fin attaches to a standard prosthetic, allowing the amputee to enter, swim in, and exit the water without needing to switch to different prosthetics. But it’s not just about swimming. Allowing amputees to return to a more active lifestyle can improve their overall well-being, according to Northwell. The Fin is printed with carbon-fiber-reinforced nylon for strength and flexibility. Conically-shaped holes control the amount of water that passes through the Fin so the relative levels of drag and propulsion can be customized for each amputee’s unique needs.

Using 3D printing to create customized and custom-fitted prosthetics has the potential to speed the process and reduce costs. Advances in and discoveries of new materials that can be used for 3D printing will extend the potential medical applications.