This is an engraving of a drawing bench that was used to produce a strip of gold the exact thickness of the desired coinage, from the previously rolled ingots. From this strip, the planchets would be cut.
Source: Taxay, Don. The U. S. Mint and Coinage, An Illustrated History from 1776 to the Present. New York, NY: Arco Publishing Company, 1966, page 163.