http://youtu.be/G0ouOqDo2gI

A father built a prosthetic hand for his 12-year-old son using a 3-D printer.

Paul McCarthy, from Marblehead Massachusetts, made the inexpensive yet functional prosthetic hand for his son Leon, who was born without fingers on one of his hands.
The family had been told when Leon was very young that he needed to get used to using his hand without prosthetics and try to acquire a full range of abilities and motion, but a doctor recently said they should start looking at prosthetic options.