Electro-Mechanical DIY...

I’ve been pondering making a few instruments for my next CR album, and in doing so have been perusing Iner Souster’s pages as a source of inspiration and ideas, along with my normal and perfectly healthy obsession with All Things Neubauten. After successfully making the Bogdon Box Bass, I’ve realized that there really isn’t a lot to these sorts of things. What’s your favorite electro-mechanical (as opposed to synthie type stuff we normally cover here) DIY instrumentation? Have you built something odd? Discuss.