He hopes his 3-D printing construction method, which he calls Contour Crafting, will create a way to build homes for a fraction of the current cost. While he can’t do anything about the price of land, Mr. Khoshnevis said his technology would build a house in a day and cut down on the construction cost by 30 percent.

The method supplies a concrete mixture through a robotic gantry guided by a computer. Instead of a hand laying a line of bricks, the machine’s nozzle pours a shaped tube of concrete, following the entire outline of the house in one lap. The next go-round adds another layer, building until it is time for the roof to be added by a crane, then perhaps another story on top. For apartment buildings, Mr. Khoshnevis has plans for a machine that will climb the building as it builds it.

He aims to build a full house in one day without a human hand, a goal he says will happen within the next year or two. Though Mr. Khoshnevis started the 3-D printing construction movement in 1996, the Chinese company Winsun has already printed homes and apartments using a similar method, though creating the pieces off-site and assembling them at the location of the structure. Mr. Khoshnevis says American building codes have created a longer timeline for 3-D-printed houses to ensure their safety.

For cities in the far future, Mr. Khoshnevis and NASA are working together to build structures using Contour Crafting on the moon from materials available there. If your great-great-great-grandchildren end up living on Mars, it might be one of these machines that builds their houses.

Mr. Khoshnevis has some high-powered fellow believers. Eric Schmidt, executive chairman of Alphabet, Google’s parent company, recently listed 3-D-printed construction on a list of the “next really interesting moon shots,” referring to ideas that will radically shape the future. “We can build them with 100 percent recyclable materials,” Mr. Schmidt said. “So it’s another good reason from an environmental perspective.”

Arthur Mamou-Mani, director of Mamou-Mani Architects and FabPub as well as a lecturer at the University of Westminster, said humans would be much more empowered to face challenges and respond with creative solutions as a result of the availability of 3-D printers and other fabrication machines.