Without a doubt, this is one of the best and simplest inventions I've seen in a long time: A long strip of calendar days, made with a material that sucks ink to tint one complete number each day. Genius.
Created by Oscar Díaz—no family relation, even while it's my brother's name—the 420 X 595 mm Ink Calendar actually works. Oscar says that it's not designed to be one month only, but the whole year:
The ink colors are based on a spectrum, which relate to a "color temperature scale", each month having a color related to our perception of the weather on that month. The colors range from dark blue in December to three shades of green in spring or orange and red in the summer.
You can see it now at the Círculo de Bellas Artes in Madrid. And then, you can go have some gambas a la plancha, iberian ham, and other delicious tapas with some chilled white wine from Rueda. [Oscar Díaz via Dezeen]