"Interchangeable parts" made mass production relatively easy in many industries.
Interchangeable parts will be parts (segments) that are, for useful purposes, indistinguishable. They are made to determinations that guarantee that they are so almost indistinguishable that they will fit into any get together of a similar kind. One such part can uninhibitedly supplant another, with no custom fitting, for example, filing. This compatibility permits simple get together of new gadgets, and less demanding fix of existing gadgets, while limiting both the time and aptitude expected of the individual doing the gathering or fix.