Since Spain opened the first 3-D–printed pedestrian bridge in 2016, the push for printed architecture seems to be accelerating. Shanghai inaugurated the world’s longest printed concrete bridge in January, and the first-ever printed steel span is set to cross a canal in Amsterdam this year. Beyond bridges, the first 3-D–printed homes available to rent—five bulbous buildings in the Dutch city of Eindhoven—should hit the market by this summer.

Some of the artsy, even zany, designs seem like architectural fantasy. But some experts believe these novel prototypes could herald a major shift in the construction sector. “The building industry is very stubborn” when it comes to change, says Capt. Matthew Friedell, who leads the U.S. Marine Corps’ 3-D printing operations. But “once we prove 3-D printing’s advantages for construction at scale, its adoption will increase rapidly.”

In usual bridge construction, skilled workers mix concrete and pour it into plywood molds called forms. Large-scale 3-D printers, by contrast, pump out quick-setting concrete slurry from a nozzle on a crane or gantry arm that moves on rails, guided by a computer, to create entire structures layer by layer. Instead of making new forms for every piece, builders can reuse one printer to create a variety of projects. Without requiring forms—or skilled workers to construct them—a printer can get to work faster, with fewer materials and less labor.