Check here http://www.contourcrafting.org/ the contour crafting technique.
"Contour Crafting (CC) is a layered fabrication technology developed by Dr. Behrokh Khoshnevis of the University of Southern California. Contour Crafting technology has great potential for automating the construction of whole structures as well as sub-components. Using this process, a single house or a colony of houses, each with possibly a different design, may be automatically constructed in a single run, embedded in each house all the conduits for electrical, plumbing and air-conditioning." in http://www.contourcrafting.org/. Check also the videos.