Sentence:  "Flat chasing in sunken or low relief is a technique by which the ornament is formed by beating down the ground from the front. This is done in essentially the same manner as repoussé work, where the ornament appears in high relief, but the design is punched from the face of the silver plate. ... Sometimes, instead of applying a freehand design, the <WSD>chaser</WSD> covers the greased suface with a paper pattern in which the design is pricked with pins." 
Meaning of the word marked with <WSD> tags:  Someone who chases (decorates) metal; a person who decorates metal by engraving or embossing. (from 18th c.)