The MIDI format has long been used to create some banging electronic music, so it’s refreshing to see how [John P. Miller] applied the standard in his decidedly analog self-playing robotic xylophone.

[Ania’s] been working on extending a xylophone in a project called Multixylophoniomnibus. She’s fitted a piezo sensor on the bottom of each xylophone key, interfacing it with an Arduino. When a mallet ...