NASA's Innovative Advanced Concepts program just awarded a $100,000 grant to a company called Tethers Unlimited Inc. The grant will be used to develop their SpiderFab project. NASA hopes SpiderFab will eventually be able to print large space structures while in orbit.
According to the official SpiderFab project site it will basically be a large orbiting 3D printer:
"We propose to develop a process for automated on-orbit construction of very large structures and multifunctional components. The foundation of this process is a novel additive manufacturing technique called 'SpiderFab', which combines the techniques of fused deposition modeling (FDM) with methods derived from automated composite layup to enable rapid construction of very large, very high-strength-per-mass, lattice-like structures combining both compressive and tensile elements."
If the team at Tethers Unlimited can get SpiderFab running, it will save NASA a ton of money. It's incredibly expensive to build equipment capable of surviving the launch process. Everything NASA sends up has to be stress tested to see if it can survive liftoff. On top of that, each piece of equipment has to have brackets or tie-down materials created to keep it from rattling around during the launch. SpiderFab would make it possible for NASA to ship raw materials into orbit and build some of the pieces right in space, eliminating the need for much of the pre-launch expense.
This is not the only 3D printed project NASA has funded recently. They've shelled out money to develop 3D printed food and lunar habitats. They've even expressed interest in mining asteroids for rocket fuel.