Until recently, making comfortable and affordable prosthetics for the handicapped has been impossible. The amount of engineering and tooling needed to make one prosthetic arm is the same as the amount of tooling needed to make a million arms.
Thanks to 3d printing, all that tooling and iteration cycling has been eliminated.
For small or single run items, instead of going down the long path of plastic injection molding, 3d printing is all you need to create little miracles.
3d Printing Company & Injection Molding Reveals 