I'd like to submit a project that I recently completed.
This project uses a laser pointer and a couple of motors with attached mirrors to display patterns (lissajous figures) that are in sync with music. The audio data is processed by a Python script that extracts frequency information, converts that to motor pulses and send it to the Arduino (clone) via the serial interface.
I have a complete write-up here, which also has a video:
I did something similar in 1985 using DC motors and PLL to control the phase between the 2 motors so the spirograph image will remain stable. How can I do this today using stepper motors? It would be jerky?
Isn't there a way you could tune it? The output appears to be too random for it to accurately represent a musical interpretation. Sorry to add to the Debbie Downer list.