I was able to do something probably few have, which is visit one of those small hole in the wall museums staffed essentially by just a single passionate old guy assembled with his life savings, dedicated to the printing press. Incredible experience.

Anyways, it’s been about 15 years, but the thing that made an impression on me was that it wasn’t just one invention. Gutenberg basically had to assemble like two dozen separate innovations to make it all work.

The type alloy (3 metals!) had to be just soft enough to cast easily, just expandable enough to set well, just hard enough to last. How to cast in quantity and re-melt as needed. The ink had to be just runny enough to apply easily but not so runny it gets everywhere, sticky enough to stick to type, and dry at a good middle speed. The blotter to apply the ink to type. The system of wooden casing to hold the pieces together with the right spacing, that won’t fall apart. How to set up the casing. The screw press needed to have very even pressure. The paper needed to be able to slide and take ink properly without spreading but also not tear. Proper fonts and ligatures for the type. And so on…

IIRC most things stayed pretty similar for a few hundred years, mostly changing stuff like the paper feeding mechanism or tweaking ink application or minor variations in how the lever or screw work. So to be honest, Gutenberg did almost all the hard work himself. It was a big deal because a lot of these smaller inventions had to come together for a narrow purpose all at once (on top of the obvious huge historical effect of cheaper books!)