In 2017, Dutch designer Joris Laarman will wheel a robot to the brink of a canal in Amsterdam. He’ll hit an “on” button. He’ll walk away. And when he comes back two months later, the Netherlands will have a new, one-of-a-kind bridge, 3-D printed in a steel arc over the waters. This isn’t some proof-of-concept, either: when it’s done, it will be as strong and as any other bridge. People will be able to walk back and forth over it for decades.

That’s the plan, anyway. To make his dream a reality, Laarman has created a new research and development company called MX3D, which specializes in building six-axis robots that can 3-D print metal and resin in mid-air. The tech allows for large-scale objects like infrastructure to be printed in the exact spot where they’ll live, which has radical implications for the construction industry and opens up a wealth of new design possibilities.

MX3D isn’t some high-tech concept; it actually works. In February 2014, Laarman showed off the MX3D system’s ability to 3-D print gravity-defying metal sculptures in mid-air. But printing out a bridge on location is a decidedly different challenge than 3-D printing something in a lab.

MX3D isn’t some high-tech concept. It actually works.

“We thought to ourselves: what is the most iconic thing we could print in public that would show off what our technology is capable of?” Laarman says in a phone interview. “This being the Netherlands, we decided a bridge over an old city canal was a pretty good choice. Not only is it good for publicity, but if MX3D can construct a bridge out of thin air, it can construct anything.”

The finished bridge will be around 24 feet long, support normal Amsterdam foot traffic, and feature a beautiful, intricate design that looks far more handcrafted than the detailing on most bridges. Because 3-D printing allows for a granular control of detail that industrial manufacturing does not, designs can be much more ornate, and almost bespoke in appearance.

Most 3-D printers use resin or plastic to construct objects. MX3D’s bridge will be made of a new steel composite that the University of Delft created. As strong as regular steel, it can be dolloped out by a 3-D printer, drop by drop. The result? A 3-D printed bridge as strong as any other, Laarman says.

As for the printer: it isn’t much like a Makerbot or any other desktop 3-D printer. For one thing, it has no printer bed. Instead, it works like a train. Except instead of running along existing tracks, it can actually print out its own tracks as it goes along. An additive printing technology that is more like welding than squirting out drops of plastic means that the tracks can go in any direction: not just horizontally, but vertically and diagonally as well. That allows the MX3D to cross gaps, like the empty space between walls, or the banks on a river, just by printing its way across them. A useful skill for a robot to have if it wants to 3-D print a bridge, or any other large structure, for that matter.