Xiaomi Shows Off Smartphone That Can Use Full-Size Leica Lenses

Surprisingly not that expensive per unit if they literally just made 10.

The metal parts must be 3D printed I imagine?

There is, however, something especially bad about using a lens with a poorly matched sensor. The video boasts that the camera uses a 13.2mm x 8.8mm sensor (it uses the unfortunate 'full 1" sensor' terminology for this, so it could actually be smaller), which means it has less than 14% of the area of the 35mm film these lenses were intended for, and a 2.7 crop factor. The 35mm lens they show would behave somewhat like a 95mm telephoto lens.

It would presumably also need to be focused through the sensor in some laborious way, unless they've devised a clever rangefinder using other cameras on the back. And if it is using the sensor for focus and as a viewfinder, how does the aperture meant for a rangefinder work?