"Additive manufacturing (or "3D printing") has already revolutionised the design of plastic products."
Well additive metal manufacturing is not new [1] and already revolutionized the design of metal products. The Amaze project is just joining forces to think out new designed components.
[1] Example: http://www.youtube.com/watch?v=zApmGFDA6ow
Edit: There are 3 methods (I know of) for 3D metal printing:
Metal powder is fused with a laser, layer by layer.
Metal powder is sprayed at the focal point of a laser and fused / added to the object.
A ceramic mold is 3D printed and molten metal is cast into the mold.