That's quite importand moment, hands are a tool, very sensitive one, and we had it from very beginning. One can cut a part on metal lathe, producing a lot of metal chips, but after that for some very preciese stuff finish can done by hands with or without power tools(not for every 6D CNC cut part, but for spececialspecial and useful cases and for some others as well). And after that it at precision limit, more than that makes little sense (due termal expansion and all that) except some science stuff.
On other hand it needs to mention that things we may think like pretty mundane or ordinary can be quite challenging and require a lot of reading experementations if one does not know how exactly. Because indirectly there a plenty of science backed in - as an example kfof such items I can name a crucible (for iron melting).