This is interesting: a sand-powered 3D printer called The Stone Spray Project. Created by Anna Kulik, Inder Shergill and Petr Novikov of the Institute for Advanced Architecture of Catalonia, this robotic-arm device mixes plain old sand with a liquid binder to gradually create arbitrary shapes out of sand, like the sand stool pictured above.
Watch the video here to see how it works. You can also read their thesis paper that explains the entire project here.
The idea is to create objects onsite directly from local soil. In this case, it's sand. At the moment this is merely a research project, but the results are interesting. We'll be watching to see where this experimentation leads.
Via Stone Spray