Took a tour of a pretty cool facility yesterday.
They have several 3D printers; typical plastic, but also concrete and metal!
One thing they printed a while back was an AC cobra:
Couple of pics of the metal printed stuff. Its a 4 cyl engine block! The printer also has a CNC machine, so as it prints a couple of layers, it can machine features or smooth surfaces, then print another layer or so, then machine, lather rinse repeat!!
No pics of the concrete printer, but it was pretty cool too. This thing flied around on cables.