In a new YouTube video, Ryder Calm Down, a creative technologist and software engineer, shows off a wild idea he came up with. He turned his pickup truck into a big printer that can write on the road, but instead of ink, it uses water. It's kind of like skywriting but on the street.
He calls his invention, which he thought of during the pandemic, the "world's largest dot matrix printer." He had all the parts just sitting around, so he finally put them together. In the video's caption, he says, "Now I can leave drive-by messages in front of friends' houses."
The printing process works by dropping splotches of water onto the road while the truck is driven. The water is dropped carefully to shape letters and form custom messages. The system is mounted to the back of the truck and controlled from inside the cabin using a web interface. As a message is parsed, a series of tubes direct water into position and activate precisely to create shapes much like a dot matrix printer.
The Raspberry Pi is responsible for running the web interface, accepting user input for new messages and sending the command to trigger the water-based printing system. In this case, Ryder has opted to use a Raspberry Pi 4 but you could get away with using an older model like a Raspberry Pi 3 B+ or maybe even a Raspberry Pi Zero.