[Cthulhu_]

> Never underestimate what a bored machinist can accomplish in their spare time.

Put a bit broader, never underestimate what people can achieve and figure out in their spare time. I mean as a child I would build dams and channels out of stones and dirt at the beach or near rivers while on vacation, without any formal education or knowledge about waterworks. I can see how this play would end up in things like irrigation systems, aqueducts and sewage systems over time, if I were to live in a place or a time where those things were not present.

It's probably been the same with tools and art for tens of thousands of years. When people are not struggling for survival, they will experiment.