On-demand manufacturing (in space)

Since the International Space Station's humble beginnings in 1998, the endeavor has resulted in various new findings in the areas of cancer research, protein crystal fabrication, and even the cultivation of human tissue, as well as the effects of zero gravity on the human body. What we learn up there might help us cure diseases down here, but doing science 220 miles (354km) away from your nearest supplier is a tricky challenge. The research astronauts do on the ISS often requires new kinds of tools -- tools that need to be supplied using space shuttles to ferry them; a costly and very limiting method. That might change when a new technology comes to fruition that would allow scientists on the station to create their own tools... from scratch.

Hey, maybe someone needs a vase up there, who knows.

Electron Beam Freeform Fabrication (EBF3) is a process by which NASA hopes to build metal parts in zero gravity environments. The process is very similar to soldering: You take a piece of metallic wire and heat it up using an electron beam until it becomes liquid. In this form, the material can then be formed into almost any possible shape. In principle, the idea is a lot like the 3D printer, in which objects are constructed layer by layer.

The technique could one day be used by the crew of the ISS to construct new tools on the fly, eliminating the need to wait for the next space shuttle to arrive with a new batch of instruments. While still at a primitive stage, Boeing has had a vested interest in EBF3 from the very start, believing it could aid them in the construction of new types of aircraft in the future. So in a couple of years, prepare to not only see these machines get used not just by astronauts, but by at least one aircraft manufacturer as well. Star Trek's replicator may not be a too distant reality.
Oh, and speaking of Star Trek...