• Maggoty@lemmy.world
    2·
    2 months ago

    I’m pretty sure that’s just precision grinding glass and setting it at the right distances.

    • JohnDClay@sh.itjust.works
      2·
      2 months ago

      But getting the precision shape to grind in can be hard. There was something about dripping liquid glass just right, but that may have been professional espionage to throw people off.