There's various theories about how specific aspects could have been made, for example, there are several ideas about how to hand-polish granite surfaces to the

There's various theories about how specific aspects could have been made, for example, there are several ideas about how to hand-polish granite surfaces to the required degree. I haven't seen one that explains all aspects of this at once and it's intellectually lazy to say "(most of) these questions are solved in isolation, so it's not a valid question anymore", with things like the consistent wall thickness being especially difficult (and for which it would be very interesting, for example, to measure whether the miniscule imperfections mirror each other on the inside/outside, to make some deductions about the manufacturing process). UnchartedX, as far as I know, is one guy who happens to be enthusiastic about a bunch of these things. Regardless of how crazy some of his theories might be, he's sure as heck doing a lot more objectively useful work to find out things about them than insulting people on an online forum.