Punch with engraved letter

The first step consisted of engraving a letter onto the tip of a longish iron rod.

This rod then bore the individual letter as a reversed image in relief.
The rod was hammered into slips of soft copper, creating a sunken impression of the letter in the correct image.

Matrix with letter

This in turn served as the mould which had to be fitted into the type-casting instrument.
Molten typemetal was poured into the mould, resulting in a lead letter with the individual letter on it in a reversed image in relief. As the typemetal was reusable, a theoretically infinite number of completely identical and uniform letters could be produced.