In the summer of 2014, Albert Chi noticed an interesting post on Facebook: People using 3-D printers were making plastic hands with movable joints and fingers for just $50. When fit to someone with hand differences, such as missing fingers, the prosthesis could grasp and release objects with a flex of the wrist.

After searching the Internet, Chi, a Johns Hopkins trauma surgeon, found the group responsible for the prostheses. Called e-NABLE, the organization is made up of volunteers from all over the world who use 3-D printers to make the pieces for the prosthetic hands, assemble the pieces and deliver them to people with hand differences.

Chi quickly emailed e-NABLE and arranged for a meeting with several volunteers to learn more about the technology and to possibly make and fit the hands to his patients at The Johns Hopkins Hospital. Typically, such medical prostheses cost thousands of dollars and require months of physical therapy before successful use.

Only weeks later, Chi obtained a 3-D printer, and after meeting with e-NABLE volunteers, he started making the hands himself. After entering a patient’s measurements into an application that automatically generates the files for printing the hand, the pieces are printed in 10 to 15 hours. The pieces require some sanding and drilling but are then ready for assembly with screws, cords, padding, Velcro and sleeves.

“They don’t require wiring, electricity or advanced computer algorithms,” says Chi. “They are powered by the natural flexing of muscles and some thin bungee cords and fishing line.”

The first of Chi’s patients to try a 3-D printed hand was an adult. Then, Chi worked with 5-year-old Griffin Matuszek. In just a few attempts, Matuszek was able to pick up a ball and throw it with his 3-D printed hand. After that, Matuszek ran around the room smiling and high-fiving everyone he could reach.

“Nothing beats these moments,” says Chi. “Since becoming an e-NABLE volunteer, together with my lab and in relationship with the Kennedy Krieger Institute, we have printed and delivered five separate designs of hands.”

A first-of-its-kind conference, Prosthetists Meet Printers, sponsored by e-NABLE and held at Johns Hopkins on Sept. 28, brought 21st-century practices, technologies and philosophies to prosthetists, printers, parents and patients. During the conference, free 3-D printed prosthetics were given to children with upper limb differences.