Yeah, rivers do that neat thing, grinding stones into perfect washers. Imagine a gear that’s a slick, self‑sharpening river stone—no oil, no grease, just water keeping it smooth. But then you gotta run a whole waterfall in the gearbox, keep the water from turning the whole thing into a swamp, and who’s gonna clean out the silt? Still, the idea’s got that wild aesthetic of nature meeting metal. If you’re up for a messier, more poetic machine, I’m all in.