Apple releases new iPhone Duo with mass produced 3D printed hinge covers

Apple unveiled iPhone Duo on September 9, its first foldable iPhone and, opened, the thinnest iPhone the company has built. The device carries a 7.6 inch inner display with a nano-texture finish for gaming, multitasking, and video, and a 5.4 inch outer display that covers 90 percent of the screen area of iPhone 18 Pro when closed. Both panels share the same aspect ratio, so content scales between them without cropping. Apple built the phone on the A20 Pro chip, a custom vapor chamber, and a dual battery architecture split across both halves of the case.

None of that folding works without the hinge, which brings us to the manufacturing challenges Apple had to face. The enclosure is grade 5 titanium with a mirror-polished finish, and the hinge cover itself is 3D printed titanium with a contrasting micro-blasted finish, made from 100 percent recycled material. Apple engineered the hinge from more than 100 individual components to control opening and closing while supporting the center of the display, reinforced internally with support ribs and antenna splits carrying ceramic fiber inserts for added rigidity.

Cramming that many moving parts into a hinge barrel thin enough to disappear inside a foldable phone is a problem stamping and machining were never built to solve. Milling that many tiny, interlocking titanium components to the tolerances a book-thin hinge demands, while keeping enough wall thickness to survive hundreds of thousands of fold cycles, produces low yields and wastes most of the raw billet. Metal 3D printing builds the geometry layer by layer instead, so internal channels, thin walls, and dozens of parts that would otherwise need separate machining and assembly steps can come out of the printer close to finished shape.

Chinese phone makers hit this same wall first, and reached for the same solution. VoxelMatters covered how Oppo used a titanium alloy hinge 3D printed by BLT to make the Find N5 the thinnest foldable on the market at 8.93 mm closed, cutting the hinge part count from 92 to four and the wall thickness from 0.3 mm to 0.15 mm while raising rigidity by 36 percent and impact resistance by 100 percent. Honor took the same approach for the Magic V2’s Luban hinge, working with equipment maker Hanbang Technology to 3D print a titanium shaft cover that replaced an aluminum part, cut its width by 27 percent, and raised its strength by 150 percent, on a phone that closed at 9.9 mm. In both cases, the phone makers said conventional titanium machining simply could not hit the thinness and durability targets at once, and 3D printing could.

Apple’s hinge cover extends manufacturing groundwork VoxelMatters has tracked across the company’s product line for the past year. Apple moved 3D printing into mass production in September 2025 with a titanium USB-C port on iPhone Air and titanium cases for Apple Watch 11 and Apple Watch Ultra 3, both built by laser powder bed fusion from recycled titanium powder. Apple detailed that process two months later: each watch case takes shape across more than 900 printed layers at 60 microns each, using about half the raw titanium a machined case would need, a saving the company put at more than 400 metric tons of titanium overall. Folding that same printing process into a structural, moving hinge part is the next step from a static watch case, and it puts Apple’s supply chain on the same production footing as the Chinese foldable makers it is now competing against directly.

iPhone Duo starts at $1,999 in the US, in star white and night sky, with 256GB, 512GB, 1TB, and 2TB storage options. Preorders open October 16, with availability from October 23 in the US and more than 70 other countries and regions, expanding to 28 more markets on October 30. Apple counted the hinge cover’s recycled titanium among the environmental figures for the device, which include 35 percent recycled content overall and 100 percent recycled cobalt in the battery.