> intuitively for something to be this precise, the tools and equipment that "create" it should also have to be more or less equally precise. Very reasonable a

> intuitively for something to be this precise, the tools and equipment that "create" it should also have to be more or less equally precise. Very reasonable assumption that I used to have too. (Un?)fortunately it's also wrong, or at best, incomplete. :-) e.g., maybe you don't have the technology to make precisely straight lines, but if you can make a flat surface (like paper), then you can fold it in half and get a straight line. Then fold that in half and get a pretty-close-to-90-degree angle. I also vaguely recall that feedback can increase precision in a system... like you can get 2% accuracy with a circuit that has only 5%-accurate resistors by using feedback (or something along those lines). Unfortunately I no longer recall how this is done. I just remember my mind was blown when I learned it.