I chanced upon a pair of Pratt-Read keybeds from an old Hammond organ, so I thought I'd come up with some sort of optical means of detecting keystrokes. While investigating how to do this (particularly with some conversation with Seppoman), I came to the conclusion that doing so would involve an unreasonable parts count and high cost. At up to two dollars apiece, 44 slot or reflective detectors get rather expensive. Furthermore, I'd need a comparator with each key unless I use a more costly detector with logic output. I've decided to instead use a Fatar keybed.