Yep, Symmetry is the big one. Even with a computer driven CNC machine this would be hard to get as exact as they did on some of that work.
Nonsense. We can measure the diameter or molecules. That allows for making things to that scale.
Nonsense!!! Just what is the accuracy of those peices? Please quote the accuracy. Even inexpensive CNC machine can repeat accuracy to .0005”; and, intricate machines to .0001”. We can also make things “optically flat”, none of which is evident in that ancient stuff.