Instructables user RobHopeless posted instructions for building your own DIY Stereolithography setup at home. In other words, he created a DIY setup for printing 3D objects in a vat of UV-curable photopolymer resin using a laser. This is very cool because it is not only DIY, but also inexpensive. If you were to buy a commercial Steriolithography printer, you would end up spending tens of thousands of dollars. By contrast, this entire system was built for less than a thousand.
Open-source systems like these are going to fundamentally change the way that objects are produced, as they will bring the prices down to a level where everyone will be able to afford to own a printer. The dream of designing something in 123D and then immediately printing it out on your personal printer is growing nearer by the day.