Gutenberg's press was made out of a wine press. Letters were cast in lead, then lined up on a tray under the press. The tray was inked. A piece of paper was set over the inked letters, and the wine press forced the paper onto the letters. This cut the cost of a book by a factor of 300(!).

The trouble for Gutenberg was it was too easy to duplicate his press, and that combined with not being good at business led to his bankruptcy.