The robot works by using computer-controlled nozzles to spray “quick-drying liquid gypsum and concrete to form walls, floors, and roofs.” The video above shows a miniature version creating small objects from layers of the material.
From the ‘Times article:
The robots are rigged to a metal frame, enabling them to shuttle in three dimensions and assemble the structure of the house layer by latyer. The sole forman on site operates a computer programmed with the designer’s plans.
Wow. I suppose we’re a long way from seeing a true variety of designs — beyond plain gypsum/concrete — but this is still pretty amazing.