The utility of this can't be understated. In space, no one can hear your call to AAA. Like everything else with 3D printing, the first things will be small and I doubt NASA will forego incorporating redundancy in favor of sending more printers.

But I imagine the space (and cost) saving potential is huge here. I'm guessing the space station requires a number of redundant and common parts. That has a cost, a common part is more easily replaced, but has to be made to the lowest common denominator. Niche parts have to be carried in duplicate or triplicate, I'm sure. If someone could chime in, I'd like to know how much that's the case.

If my supposition is true, then this means fewer parts need share common components, and this means less weight and more room for everything else. Now if only they could 3D print better meals and more dignified sanitation for the brave members of the ISS, I'm sure they would appreciate that.