From what I've seen as an amateur that is yet fascinated by mechanical engineering: iteratively work up to the precision limits with your current methods then t

From what I've seen as an amateur that is yet fascinated by mechanical engineering: iteratively work up to the precision limits with your current methods then try to find/research a (slightly) better way of measuring and/or manufacturing. Since humanity has worked up to this point over centuries/millenia, you wouldn't need to "bootstrap" it from the beginning anymore, just choose the appropriate level of (manufacturing/measuring) precision for your usecase. Otherwise start with a surface plate. Nice summary: https://www.youtube.com/watch?v=gNRnrn5DE58 https://www.youtube.com/watch?v=gNRnrn5DE58 ("Origins of Precision" by "Machine Thinking")