JotSC post of 06 May 13 - 10:26 AM "...one could make from simple gears and replacement parts for machinery to complete artificial hearts and other prosthetic devices...if not now, someday soon."

A child's life is saved by a tracheal splint to facilitate his breathing. This device was made using a 3D PRINTER according to Science Daily. The blog cites the write-up of this in the current issue New England Journal of Medicine.

I prefer to consider that this type of use of 3D is more important than moaning about the possibility of making a gun.

3D printed prosthetic