There's a Kaossilator in my guitar! No, there's a guitar in my Kaossilator!

By routing the four buttons on a Kaossilator to the buttons on a Guitar Hero guitar, James Haskin has created one of the coolest little electronic instruments I’ve seen in a while. The resulting mash-up makes it much easier to play the Kaossilator as an instrument rather than a standalone box on your desk.

Best of all, James posted the instructions for building his device for all and sundry to recreate. Great success!
via Make