Inside a warehouse in Oakland, California, a 20-foot-high printer recently 3D-printed the shell of a tiny house—not only the walls and floor, but the ceiling and roof, and overhangs. The home took a total of 24 hours to print; similar homes will soon be trucked to backyards in nearby cities.

Mighty Buildings, the startup that developed the technology to print the home, says that by automating more of the construction process, it can make homes more affordable. Compared to an average house in California, the new homes cost as much as 45% less. They’re also less expensive to build than other factory-built housing.

The company isn’t the first to use 3D printers to build homes; an entire neighborhood of 3D-printed homes is being completed this year in Mexico. But because the new process can print more elements of a house—the homes in Mexico use 3D printing only for the walls and floor—it helps reduce the cost further.