On’s Cloudboom Strike LS is an energy-returning running shoe that shaves weight and complexity by leveraging some of the best efficiencies of 3D printing. 

To produce a Lightspray shoe, the robot arm holds the outsole up to a sprayer. The arm rotates the shoe, while the spray extrudes TPU almost like a fancy garden hose nozzle, spiraling the stream as a helix. That stream lands onto the last as a single continuous string, bonding to the outsole and to itself without glue. But even though it’s a single material, On can still tune the breathability, stretch, and support of the upper in different spots through two methods: moving the shoe farther or closer to the stream, or by increasing or decreasing the diameter of that helix. Heitz says that the ensuing material is so form fitting that On’s athletes have opted to wear the shoe without a sock.

On claims this production method on the upper isn’t just faster, it reduces 75% of the carbon footprint of that part. (The TPU is technically recyclable if the shoe is deconstructed, and On says it could use a recycled TPU in their shoe.)

Source: Fastcompany