Researchers from the School of Mechanical and Materials Engineering at Washington State University have built a 3D printer that can use sorted (simulated) Lunar regolith (moon dust) to print out "crude" objects. This is the premise of a novella I'm working on, so it's pretty exciting to see:
Amit Bandyopadhyay and Susmita Bose, using simulated lunar regolith that are analogies to moon rocks, have used 3D printing to create a number of crude objects. The simulated regolith, found on Earth and supplied by NASA, contains silicon, aluminum, calcium, iron and magnesium oxides but behaves like silica when melted by a laser. Once the regolith is melted, a 3D printer creates objects out of it layer by layer.
Using moon rocks shaped by 3D printers as building material or simple spare parts and tools would vastly decrease the expense of building and maintaining a lunar settlement. 3D printing also has considerable promise for Earth bound construction.