Inspiration can strike in the most unexpected ways. For On’s innovation team, it came from a hot glue gun on Halloween. Johannes Voelchert, a senior member of the team, watched a video where a crafter squeezed a thin filament of hot glue into a fluff of spider web. This sparked the idea of creating a shoe in a similar manner. Instead of dismissing it, the team at On embraced the idea with enthusiasm.

Four years later, what began as a one-person experiment expanded to a team of 20 designers and engineers at the Swiss footwear company. The result is Lightspray, a groundbreaking method in sneaker production. By placing a last (or foot form) on a robot arm, On can spray a shoe’s entire upper (its top part) from a single continuous filament in just three minutes.

This innovation is significant because the upper is the most challenging part of a sneaker to produce. While outsoles are made in molds, uppers involve the complexities of traditional garment production, including various fabrics, tension wires, stitching, and glue. “Modern shoe making is not so modern,” says Heitz. “It’s just using 2D patterns… and we’re trying to wrap them around a very complex 3D shape.”

Producing an upper traditionally involves numerous suppliers and can take days, sometimes even weeks, due to real-world logistics and shipping. In contrast, Lightspray shoes consist of just five parts and can be constructed in six minutes total.

Lightspray technology made its debut with the Cloudboom Strike LS, a shoe first offered in a limited run in April and set to be available again this fall for $330. This innovation aligns with major trends in footwear, such as the industry’s exploration of 3D-printed products. Examples include Adidas’s Futurecraft 4D outsoles, Nike’s Zoom Superfly Elite track spikes, and Vivobarefoot’s upcoming custom-tailored footwear. The goal is to enhance efficiency and performance control, though additive manufacturing has yet to revolutionize industry production standards.

Meanwhile, performance running shoes are becoming both bouncier and lighter. This trend began with Nike’s marathon-breaking Zoom Alphafly, which returns as much as 4% of someone’s stride, and continues with products like Adidas’s Adizero Pro Evo, an energy-returning running shoe weighing just 130g. On’s Cloudboom Strike LS also follows this trend by leveraging 3D printing efficiencies to reduce weight and complexity.

To produce a Lightspray shoe, a robot arm holds the outsole up to a sprayer. The arm rotates the shoe while the sprayer extrudes TPU, spiraling the stream as a helix. This stream lands on the last as a continuous string, bonding to the outsole and itself without glue. Despite being a single material, On can adjust the upper’s breathability, stretch, and support by changing the distance and diameter of the helix. The material is so form-fitting that athletes often wear the shoe without socks.

The upper production stage takes a few minutes. After that, one robot arm passes the shoe to another robot, which sprays the shoe with color that cures in three minutes. The shoe is then ready to wear. This method not only speeds up production but also reduces the carbon footprint of the upper by 75%. The TPU used is recyclable, and On suggests that recycled TPU could be utilized in future models.

“One of the visions was, imagine if you go to a race, you have one of these robots with you, and on race day, if it’s wet or dry, the robot sprays you a perfect shoe for the moment,” says Heitz. “And at the end of the race, you take it off, recycle it, and go to the next race.”

Currently, On is focusing on the production and performance of the Cloudboom Strike LS before refining its environmental impact. While the carbon fiber energy-returning plate is recyclable, it requires significant energy to process. Long term, On envisions using Lightspray to shift production from Asia to local markets worldwide, expediting production, lowering impact, and responding to trends more quickly.

“There are no limits to this technology,” says Heitz. “You can produce what you want, where you want, and only as much as you want.”

By Impact Lab