The Coffee Drip Printer is a curious contraption created by RIT photography professor Ted Kinsman. It can print out your digital photos, but instead of buying pricey ink for the prints, all you need to do is give the machine some coffee.
The printer is powered by an Arduino microcontroller with 32KB of memory, which allows it to store and print an ~80×100-pixel photograph. The photos are low-resolution, so they’re best appreciated from a distance. And it does print human faces pretty well.
“The machine allows experimentation with drip height, drip size, drip chemistry, spacing of drips, and especially the paper that the drips fall on – all of these affect the image results,” Kinsman tells PetaPixel. To prepare a photo for printing, Kinsman takes a low-res image and adjusts the curves to make the darks darker.
Each of the pixels is turned into a number from 0 (no coffee) to 256 (the largest drip size). The size of each pixel is controlled by determining how long to open the drip valve for — the largest drop (and darkest pixel) requires the valve to be open for 63 milliseconds. In this way, the machine currently can do 53 different shades of coffee.
Stepping motors control the x-y positioning of the drip valve over the paper that’s being printed on. Each print requires about an hour to print and a full day to completely dry.
Here’s a video showing the drip printer in action:
The machine could print with pretty much any liquid you give it, but Kinsman chose coffee due to its price and availability.
“Since I always have left over coffee, I thought it would be a fun medium to play with,” he says. “Just about everyone can relate to coffee and this medium is often used to get people interested in what the machine can do.”