Mike Cook made this Junk Box Monome:

A Monome is basically a simple eight by eight grid of push switches and lights. However, the official Monomes have always had a nod towards eco friendliness by incorporating renewable wood in their construction. Well I wanted to go at least one better and use parts that I already had in my junk box, or surplus obsolete parts I could scrounge, all based on a Arduino. This dictated the electronic and mechanical design, resulting in a unique variant on the Monome theme, which is why I call it the Econo Monome.

Let’s kick off by saying that 40 years of working, and playing, with electronics has given me a junk box that is perhaps deeper than most people’s, your mileage may vary.

Cool reuse of old junk, eh?