3D printing is a fascinating technology. It's essentially a robot with a print head, and it melts a substrate and then arranges the molten substance into a pattern to let it harden. Using this process to build layer upon layer of whatever material you use allows you to literally print a three dimensional shape from a file on your computer.
Hack n mod recently featured a Green 3D Printer that is entirely solar powered and uses what is probably the most abundant substrate on the planet: Sand.
Yes, this printer uses sand to produce glass printouts. Not only that, but it uses sunlight to melt the sand. This in it's self is incredible. This is apparently a working prototype of the system, because it is not entirely automated. The printing process is manually controlled by a camera and a remote control. I'll be excited to see a fully automated one that can print and add sand by itself.
Geekiness aside for the moment, there are some amazing political aspects of 3D printers. Like all technology, it will eventually be cheap enough to have in our own homes. A home manufacturing system that will make most factories obsolete. Open Source varieties like the RepRap, MakerBot, and now the Ultimaker, are already somewhat affordable, at least compared to current proprietary versions. And the RepRap is designed to be able to make it's own parts, so that you can print one out for a friend. The RepRap's goal is to be able to make 100% of its own parts, including circuitry and motors, allowing it also to print whole electronics.
The political, and economic fear is what will happen when people not only have the power to download music online for free, but also their own music player as well. Self sufficiency is scary to economic parasites like Apple and Microsoft, and other manufacturing companies. The Accepted Business Model is becoming obsolete. The consumer is slowly beginning to not need the supplier. It is the nature of the universe, that all systems will achieve balance. Animals will adapt to their ever changing environment to not only survive, but also thrive. Those that resist change will be scattered to the wind. That is not a prediction, that is Darwinian Fact.
The Music Industry has already shown that it is unwilling to change, as well as the film industry, and software industry. And as 3D printing technology develops, more and more freedom shall be given to the common folk like you and I. It is said that Science Fiction leads to Science Fact. Just as space travel was first conceived in novels even before man developed the ability of flight, so too will the end of world hunger, conceived by Gene Roddenberry in Star Trek with his replicator technology, be brought to us by this amazing technology.