3D Printing is phenomenal technology, and if as VGuyver points out, metal printing can produce stuff as good as or better than common, there's a future for it. But like with things like caseless firearms ammunition, the problem is to take something that we know can work on a small scale, into something that's suitable for mass production. That'll be a few years from now, but we know that the concept is workable. It's just completing the steps to make it practical for mass production.