Marko, the developer of the open-source roast logger Artisan, and Paul, a human-computer interface specialist, came across an affordable true color sensor board and ordered some samples on the spot. The evening they arrived, one was wired to an Arduino and dropped into an Ikea box with some quickly assembled LEGO to hold the coffee sample.

That simple rig was already able to tell the roasts apart by color, which was enough to know the idea would work.

Clever as the Classic was, new electronic modules made a better product possible. The next Tonino gained a bright OLED color display and wireless operation, using components from the startup TinyCircuits in Ohio, and it shrank to something you can hold between two fingers.

Its wireless charging base is cut from Kraftplex, a fully organic material from Germany certified as safe even to children's toy standards. It is 100% cellulose, made from sustainably cultivated softwood using only water, pressure and heat. Its parts fit together without glue or screws, so it can be repaired rather than thrown away.

Thanks to Sonia, Çetin, Jürgen, Ralf and Rami for their support along the way.