davedarko
What the heck is it and how does it work?
For every day you do the thing you track, you flip a switch. For every month the switches are in series, so if you flip every switch in a month, the LED for the month will turn on. At first I thought I could make it smaller and therefore a bit cheaper, but that didn't turn out like I had hoped at all (see this log).
Choosing switches
At first I thought using a red 5P (P as in position/pin) switch for week days and a 2P blue switch for weekends could be cool, but the gap between each new row made it impossible to rout that AND have numbers next to it. So I opted for 10P dip switches for most of them, one 8P dip switch and seven 1P dip switches.
LEDs
I just like to use big 10mm LEDs in projects when I can, like in the #BINCL - binary coded decimal 10mm LED clock project, very haptic leds.
Robert Wallhead
blinkingthing
Dávid Máté
Mine would always be dark, because in any one month, I'll miss a day of any given thing (exercise, eat vegetables, build something, etc...). If you gave each switch a resistor and put them all in parallel, you could use current meters to make an analog version that isn't all-or-nothing, for example: I ate vegetables 35% of the days in March, hurray!
Edit: current meters won't be linear, unless they have a very low resistance. Summing the currents into an op-amp virtual ground would be better.