Gutenberg’s key innovation was really in the typecasting process. Before Gutenberg’s time, creating letters out of metal, wood, and even ceramic was extremely time consuming and difficult to do in large quantities. Gutenberg revolutionized hot metal typesetting by coming up with an alloy mostly made of lead that could be melted and poured into a letter mold called a matrix. He also had to invent an ink that would stick to lead.
The Monotype System is an exquisite piece of engineering, and in many ways represents a perfection of Gutenberg’s original workflow using Industrial Age technology. It’s also a fantastic example of early “programming” since it made use of hole-punched paper tape to instruct the operations of a machine—an innovation that many people associate with the rise of computing in the mid-20th century, but was in use as early as 1725.