It is an interesting chicken/egg problem when we (humans that is) build things more precise than anything else we've built which inevitably require tools that are not necessarily as precise as the things we're building. If this story makes you wonder how the CMM got as accurate as it is, this might give some ideas [1]. When I was taking a machine shop class in college it occurred to me daily that despite how challenging it might have been to get some part down to a thousandth [2] from where you want it, but that is with tools capable of that or better and with measurement tools capable of the same. I have a lot of respect for the engineers who have managed to iteratively increase the precision and accuracy of our tools.
[1] https://www.reddit.com/r/askscience/comments/1o404y/how_are_... [2] http://www.southadams.k12.in.us/webpages/machinetrades/machi...