I'm a chemical engineer and I've worked in some old plants. Before modern electronic control, everything was controlled by pneumatics. A control loop would literally be something like a pressure gauge connected to an air valve, so that when pressure increased the air flow would change and proportionately close off another valve upstream, and when it would decrease, the air would open the valve up. There were also complex logic circuits set up this way entirely with air pressure. Really amazing stuff when you can look at the control panels because operators were opening and closing air valves to control everything and it works just like an analogue circuit, but it's all air pressure instead of voltage and air lines instead of wires.

Oh that is indeed fascinating!

Especially when you consider that it is these kinds of forces at work, at a different scale and medium, anyway.

I think some kind of combined water/air pinball machine could be constructed, with the right balance in choice of materials for the ball, it could result in a playable pneumatic pinball mechanism.

It's just a matter of leverage. ;)