From lifesaving implants to cutting edge fashion, 3D printing is the gift that keeps on giving. What will this additive technology do next? Well, 3D print a steel bridge in mid-air, of course.

MX3D, a research and development startup company, will use robots to 3D print a pedestrian bridge across one of Amsterdam’s canals. The versatile six-axis robotic arms will ‘draw’ steel structures in 3D, starting from one side of the canal and building across until it reaches the other end. The robot will also print its own support, which allows it to work autonomously. The location of the bridge will be announced soon and construction is set to commence in 2017.

“This bridge will show how 3D printing finally enters the world of large-scale, functional objects and sustainable materials while allowing unprecedented freedom of form,” designer Joris Laarman said on the project Web page. “The symbolism of the bridge is a beautiful metaphor to connect the technology of the future with the old city, in a way that brings out the best of both worlds.”

Animation of robotic arms 3D printing a bridge. MX3D

The team has been able to overcome the shape and size restrictions of conventional 3D printing. MX3D engineers spent a lot time perfecting the robotic printer, which they say first started off as “worm-like blobs.” A few things did go wrong along the way, “a welding machine exploded, nozzles got stuck and the robot got destroyed.” Eventually—after “endless testing”—MX3D engineers were able draw complex sculptures in mid-air and then speed up the process.

"What distinguishes our technology from traditional 3D printing methods is that we work according to the 'printing outside the box' principle," said Tim Geurtjens, chief technology officer at MX3D. "By printing with six-axis industrial robots, we are no longer limited to a square box in which everything happens. Printing a functional, life-size bridge is of course the ideal way to showcase the endless possibilities of this technique.”

MX3D will work with the construction firm Heijmans and software company Autodesk.