A MAKE reader writes in with a bit of speculation on Jeep’s water fall –

“This is very cool and it doesn’t seem like it should be that hard to do. The tricky part would be finding affordable electronic valves that could open and close fast enough. They say it is similar to an inkjet but an inkjet works one of two ways, (a) desktop inkjets dispense ink into a chamber then heat it until the expansion forces it out onto the page, (b) continuous inkjets like those used to print addresses on mass mail pieces use a continuous drip of electrically charged ink droplets. The droplets it doesn’t want to fall on the paper are drawn out of the stream by a charge next to the falling droplet stream. “Link.