If it is not buttonmaker then the closest I can find is Lattener/Lattouner or Lattensmith - people who made things out of Latten. Further searches show that Latten is a copper/zinc alloy resembling brass used for church ornaments, monumental brasses etc from the Middle Ages onwards. If a Lattener or Lattensmith made the objects could your chap be a Lattenmaker eg someone who blends the metals to make the alloy Latten.