According to a Feb 1, 2013 story in IO9, a design firm named Foster+Partners plans to partner with the European Space Agency to combine the concept of inflatable structures and 3D printing to build structures on the lunar surface.
The idea is that an inflatable module, similar to the ones being developed by Bigelow Aerospace, would be transported to the lunar surface and then deployed. Then a 3D printer, using available lunar regolith, would layer a protective shell over the inflatable module, protecting it against radiation and other hazards.
Each module would be able to accommodate four astronauts. Several would be set up and connected as needed to construct a lunar base.
3D printing using lunar regolith has already been tested using simulated material at the School of Mechanical and Materials Engineering at Washington State University. The concept can be used to build spare parts and tools using lunar regolith as well.
Currently Foster+Partners is in the design and proof of concept stage. The company intends to build a small scale model of a lunar building in a vacuum chamber using Earth based regolith simulate.