Various implementations of Singing coils and associated off-label music generation:

• Stepper motors, or what I imagine a hurdy-gurdy would look like if developed by a civilization of robots.
• MRI singing [research paper] [githubl]
• Floppotron - Sweet Dreams
• 3D printer stepper motor tunes
• Dot matrix printer 'Eye of the Tiger'
• Singing Coils
• Tree Wave - Sleep Fantastic shoegaze made with chiptunes/various hardware hacks.