There must be some folks like myself still alive and old enough to remember a device popular in the 1970’s called a Colour (for some reason my spell checker only likes the English version) Organ.  It consisted of a box with light bulbs that were modulated to sound (usually music) behind prismatic glass so that colourful (spell checker again) patterns that flashed with the music.

Some were single channel using one colour, often an intense green, and others were multi-channel where they’d assign red to bass, yellow or green to mid-range, and blue to high frequencies.

Back then LEDs of significant brightness didn’t exist so incandescent lamps were used, usually 120V which required triacs and complicated driver circuitry.

I thought it would be cool to make a modern version, one could create many more channels using a DSP and a fast Fourier transform to separate the audio into many more channels and then simple driver transistors and low voltage DC to power bright LEDs of colours across the visible spectrum.

But, an essential component, prismatic glass, with a sufficiently small pattern to create a good display seems difficult to locate.  Home Depot and Lowe’s seem to carry only a prismatic plexiglass and the pattern is to large and plain to be useful.