[roboruler]

Use compressed air instead of steam as it will be much easier and safer to work with. Buy a heap of cheap pneumatic solenoids from aliexpress and a high flow 12v air compressor and some air tanks. Run the solenoids over a relay bank using an arduino mega. This will be the cheapest way of building what you want.

I think it will be a fun activity trying to tune all the different pipe lengths.