Stainless Steel Printing
From this CrunchGear entry: 'The future of fabrication is here: Shapeways announces stainless steel printing'
Much if not most of 3d printing uses modified inkjet printers. Ink is substituted with other mediums.
The incredible accuracy of the printer heads deposit nano-scale droplets exactly where they need to be. The end result is a useful or interesting object.
Where is this Technology Headed?
1. Desktop Manufacturing
In the same way huge computers shrunk to the desktop while becoming vastly cheaper and more powerful, desktop manufacturing is following the same trajectory.
2. Self Replication
Desktop fabricators capable of manufacturing all of it's own parts, to be assembled into another unit, will by nature quickly spread and improve in a self reinforcing loop.
3. Open Source Network Power
These systems will allow the grass-roots production of new continually evolving computers. The compounded power of countless networked enthusiasts around the world will pour ingenuity and creativity into new systems you can manufacture at home. Gadgets, cell phones, ... you name it... will spill from home hobyists and Universities into the marketplace in the same inexpensive way as iphone apps and the Linux free operating system.
As the hardware, circuitry and software continue to evolve, they will be capable of manufacturing and becoming robots which can self replicate.
5. Fabricating at the Molecular Level
Imagine a molecular printer. Cartridges filled with each element of the periodic table, the raw materials to create literally everything in the universe.