I’m pretty sure they would have the pieces made by machine of course, but I’m pretty sure assembly would be more efficient with a machine but because of the room for error on a machine, probably hand placed. In a video by MoYu, the 3x3s are being assembled by workers by hand.
Yeah, I bet you're right. It would probably be next to impossible to assemble a puzzle entirely hands-free, especially when thinking about how tough it would be for a machine to assemble the core with out any complications like cross threading or sub-par tensioning. I did find one video (which might be the one you're talking about) where puzzles up to 4x4 are assembled by hand: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-4xMlfnVjfFg.html
Glad to have you along for the ride 🛫🛬💥 It's good to see people actually like these videos, and I'm not completely wasting money on debatably overpriced plastic. Hoping to make future videos better and more worthwhile.