John Schull, founder of e-NABLE, acquaints, Johns Hopkins surgeon Albert Chi with a prosthetic device made by e-NABLE volunteers.

Based on a patient’s measurements, a computer application generates all of the files needed to print a hand. The printing process takes about 10 to 15 hours to complete one hand.

A 3-D printer melts plastic and then deposits layer upon layer—similar to how a hot glue gun works—of plastic to create the shape of each piece of the hand.

After printing the pieces, e-NABLE volunteers sand each one to ensure they are clean, smooth and ready for the next step.

After sanding and drilling, the pieces are assembled with screws, cords, padding, Velcro and sleeves.

Johns Hopkins trauma surgeon Albert Chi marvels at how a completed 3-D printed hand is powered by the flex of a wrist.