"Sub-Millimeter" may sound impressive to a novice, but with very simple tools like a hand file you can work on metal with a precision of a thousandth of a milli

"Sub-Millimeter" may sound impressive to a novice, but with very simple tools like a hand file you can work on metal with a precision of a thousandth of a millimeter. So yes, this is impressive craftmanship but nothing that would rewite history of technology.