David Sengeh tinkers with his design for a 3D-printed prosthetic socket. Photo: Allegra Boverman.

Growing up in Sierra Leone, David Sengeh knew all too many amputees. Now studying at the MIT Media Lab, he talks about his idea of redesigning the socket that connects an artificial limb to a human body — and his dream of creating custom-designed, low-cost, comfortable sockets that 3D printing technology could make accessible to anyone, anywhere.