3D Printing has been around for a while. Until recently it's been a technology that's relegated to the design process, where designers are able to make plastic prototypes much more quickly. Neri Oxman at MIT's Media Lab has a vision for 3D printing much bigger than the current reality. She sees the advancements in 3D printing being used to construct buildings. I've seen concept designs for all kinds of robotic building techniques, but not using the 3D printing concepts. This kind of technology is a ways out, as right now most 3D printers are using plastic. Though some are starting to use metal, and Neri wants to get them working for concrete.