I found this “Ink Calendar” by Spanish product designer Oscar Diaz that I just had to share. Ink spreads across the numbers to indicate the day of the month. Both the ink and paper are changed on a monthly basis. The ink colors vary throughout the year, ranging from dark blue in December to red in the summer. This calendar was designed for an exhibit called “Gradual” for the London Design Festival.
From what I gather, it is not on the market. Perhaps he is still working out the timing for February . . . Check out his other designs at www.oscar-diaz.net