Adidas unveiled their latest 3D-printed shoe last night, the Futurecraft 4D. The shoe is a huge improvement on their last 3D-printed runners, which were more of a concept than an actual product.

The new version is better suited for mass production – Adidas plans on selling 5,000 pairs this upcoming fall, which will scale up to more than 100,000 pairs by the end of 2018. While the company hasn’t announced the price, expect the first run to still be priced as a limited edition shoe. The first 3D runners retailed for $333, but sold secondhand for many times that.

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To create the shoes Adidas has teamed up with Carbon, a Silicon Valley-based 3D-printing company we’ve covered before. The startup, which has raised over $200M from Sequoia Capital, GV, Yuri Milner and others, is focused on making 3D printing a viable manufacturing method for large-scale production across industries.

The key to turning 3D-printing into more than a novelty used only for prototyping is speed – which is what Carbon prides itself on.

Using a method called Digital Light Synthesis the startup is able to print objects up to 10 times faster than other 3D printers. The difference is that instead of printing an object layer by layer from the top down like traditional additive 3D printers do, Carbon’s process is continuous and starts from the bottom.

The liquid resin material also allows for a much more flexible final product compared to the material used by traditional 3D printers.

Carbon’s machines use digital light below the printing surface to turn the liquid resin into a solid object. The object, in this case the shoe’s midsoles, are pulled up and literally formed from the top down.

The image below should help you visualize the process.

The object being printed doesn’t stick to the printing surface because it’s never actually touching – the surface is permeable to both the digital light and oxygen, which is pumped through the surface to always maintain a ultra-thin layer of air between the printing surface and object being printed.

After the midsole is printed it’s attached to the top of the shoe, which is made from fabric using traditional manufacturing methods.

Sound complicated? It is. But the end result means that companies can use Carbon’s technology to 3D print objects at scale. Which is exactly what Adidas is planning to do.

For them, the benefits also extend beyond speed. 3D printing allows the shoe company to unlock performance-enhancing design modifications that would have been impossible with other materials like foam.

So how does this help you, the end user?

Adidas knows that to perform at their best, athletes need different points of density throughout their midsole. A runner may need a firm toe spot and softer heel, etc. To achieve this with regular shoes, manufacturers need to glue together different pieces of foam with varying densities.

But with Carbon’s 3D printing process they can simply change the geometry of the lattice to make different areas firmer or softer.

Essentially, different patterns result in different density and feel. For example, check out how the density of the midsole below changes throughout.

The finished product is a shoe that feels really good. The shoes are springy but firm at the same time – which is exactly what Adidas is trying to accomplish. And since they’re 3D printed all it would take is a slight tweak of a design file to make a pair more springy or stable.

Because while the first step is just to get to mass-production, Adidas eventually sees a future where everyone will be able to have their own 3D-printed shoe, with the midsole totally customized to their individual needs.