Any given thing will sooner or later be used as musical instrument. Even dot matrix printers, you ask? Even dot matrix printers. Paul Slocum hacked the firmware of his 1985 dot matrix printer to let it print in different frequencies.
The printer creates sound from the print head firing pins against the paper and the vibration of the stepper motor driving the print head back and forth. To generate different notes, the software adjusts the frequency of the printing process. Higher pitches tend to come from the firing of the pins against the paper, and lower pitches come from the rattle of driving the stepper motor.
Users can play the “instrument” via a connected control pad with eight buttons, each assign to a tone.
Interestingly, it prints real pictures while you play it. ^_^