The outer case isn't 3D printed - it's an off-brand iPhone 12 Pro cut in half. The split screen hack is just FloatingDock for Cydia. And the triple lens camera enclosure is a non-functional mockup.
To imply the case was 3D printed, they show a Blender file - in reality, this was only used for promo animations. The printer from the video can't output that kind of product, so they took a cheap iPhone lookalike (https://www.youtube.com/watch?v=Z5mSrWqw3No) and cut it in half, combining it with the Razr hinge.
The triple rear camera is from the off-brand iPhone, with no functional sensor behind it. A second device is used to demo the real camera - one with a rough outer finish, and a likely-unfinished back which is never shown. You can identify this device in the videos by the 4 lenses on the front.
These flaws are certainly nitpicks - the project overall remains nothing less than amazing. Surely any hacker would brush these off as artifacts of the creative process.
Which is why I'm deeply disappointed to see the creators diminish their own achievements by outright lying about these minor details. And with such slick editing too. It leaves a bad taste in my mouth.