I followed up Mark Hammer's suggestion of a simplified "QuadraFuzz" with three tube sound fuzzes for high, medium and low frequencies mixed into a single output. This works fine, it's not super effective at reducing interaction between different strings, since adjacent strings are less than half a octave apart, and we have about 2 octaves per frequency band. Plus I used simple passive filters. But you can tune the fuzz on the high notes separately from the low notes, which is good.

Charles R. Fischer designed the "EM Distortion Box" which had a "spectra" LM334Z current regulator for the CD4049 to simulate amp "sag". May as well add the LM334Z.

So I could just do an Anderton QuadraFuzz with 8 channels, using 8 "Tube Sound Fuzz" modules. With a "LM334Z" current regulator, 3 Quad opamps and 3 CD4049's. But that would be a big PCB, and a lot of controls.

Or a HexaFuzz with 2 quad opamps, 1 or 2 CD4049's and a fixed mix among channels.

More likely the passive 3-band version, with the current limiter.

Since the kit would include selected CD4049's (audio performance of logic chips seems a little variable) it should be possible to get consistent results.