If you compare the Apple Watch Ultra 3 with the Ultra 2, you probably wouldn’t be able to tell they were made with drastically different manufacturing processes. The titanium Apple Watch Series 11 and Ultra 3 are not only made with 100 percent recycled titanium powder, but are also 3D-printed, a process that’s pretty impressive at Apple’s scale. 3D printing creates less waste, in this case cutting raw materials usage for the watch cases in half, but introduces new challenges, like balancing speed and precision.

Apple has released more details about its process, which involves blasting titanium dust with a laser. Over 900 layers of material, each 60 microns thick, go into a single watch case (for context, one micron is equal to 0.001 millimeters). The titanium powder used for the cases has to be fine-tuned itself to reduce its oxygen content so it won’t explode when exposed to high heat.

Printing Watch cases, rather than using subtractive manufacturing, has allowed Apple to save an estimated 400 metric tons of raw titanium this year. Apple also applied the same 3D-printing process to the USB-C port on the iPhone Air. While they’re not 3D-printing an entire iPhone chassis yet, it sounds like it’s not out of the question. As Sarah Chandler, Apple’s VP of environment and supply chain innovation, mentions in the press release, “We’re never doing something just to do it once — we’re doing it so it becomes the way the whole system then works.”