Been around for quite sometime, used a lot in rapid prototyping and blade casting (to provide a negative mould for instance).
If anyone has a 3D printer, I'd like a Weird Science era Kelly lebrock please.
I believe that the Chinese have made a 3D printed Titanium wing spar.
3ders.org - 3-meter long titanium airplane part 3D printed in one piece | 3D Printer News & 3D Printing News