a controller based on the great construction work of michael l. ;-) we used 30 of those for the interactive performance DEMOCRACY in 2011 and michael had done amazing work putting them together. it has got three push buttons which I already re-used in a couple of projects (see following posts: led controller, birthday canon machine).
based on this controller i build my own by adding two new items: one on/off switch and one potentiometer. that controller now entails three basic control mechanisms (two digital, one analogue) in one device to play around with.
below is the prototyping bread board setup to make it work with arduino.