Engineezy wanted to see if he could create a steel ball water wheel to charge a phone. He spends a surprising amount of time and effort getting the balls to roll smoothly and not jam (he takes inspiration from Wintergatan‘s marble machine). While the finished machine is an impressive feat of engineering, it (obviously) uses tons more electricity than it outputs.

It would have been interesting if he talked to some modern hydro power engineers or old water mill operators since it seems like there is a lot of overlap with hydro power generation and the problems he encountered when it came to extracting power from the balls.