Mug displays electronic messages only when filled with coffee

Latte art has become a common creative way to surprise coffee lovers, but new technologies are enabling more complicated communication through the medium of hot beverages. In the past, we’ve seen Textspresso demonstrate printed edible ink messages using coffee foam as a surface, and now Finland’s Muki is a drinking vessel with a built-in e-ink display, that shows a picture or message only when it’s full of coffee.