The Collaborative International Dictionary of English v.0.48:

Diesinker \Die"sink`er\, n.
   An engraver of dies for stamping coins, medals, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

die-sinker
    n 1: someone who makes dies [syn: diemaker, diesinker, die-
         sinker]