Play music on 3D printer motors

Parse a MIDI file; pick up to three simultaneous voices

Map note frequency to feed rate per axis, given the printer's steps per mm

Keep every axis inside its travel limits by bouncing direction, never crashing into an end stop

Emit G-code with correct timing so the tune is in tempo

A simulator that renders the tune as audio from the G-code so it can be checked without a printer

A fourth voice on the extruder motor, with the nozzle cold

Requirements