Really only 1 is needed, depending on what you want to do, there was never a BOM created for it, but I made one based on how I built mine.
It has quite a few different sections:
40106 as 6 variable oscillators
40106 as 6 fixed (or variable if you add pots) oscillators
1 4040 divider
1 4051 8 channel analog multiplexer
1 4015 dual 4 stage shift register
1 VCA with decay EG
1 4017 10 way counter
8 ch Stereo fixed mixer
2 4 way Diode ORs
Analog bass drum
4 way buffer
4070 quad XOR gate
4 4 way mults
Stereo output with separate level control for each.
Here is a picture of my build, you do not need to build it the same way, for example unneeded sections can be omitted, I opted for headers to patch with dupont cables, but of course you can forgo these and hard wire it instead, depending on what you want to build/do with it.
Some examples could be a simple drone synth, some kind of weird groovebox, a drum sound generator or primitive drum machine. Depending on what additional circuitry you add of course.
The way I built mine is pretty basic, but I used pin headers for the capacitors too so that oscillator ranges can easily be changed, and it can be reconfigured easily to do most of the examples I listed above.
I eventually plan to build one into a case with just panel mounted controls rather than pcb mounted, and various patch point and probably a couple of filters, to make a kind of mini modular, all running off a 9v battery
It is probably worth looking at the hackaday articles for a better idea of what it can do.
Here are a few more of my noodlings:
It need not sound like that though, I have also made it do some very nice drone stuff as well, but no video clips of that.
I’d say it is a couple of hours build for a relatively competent solderer, it is pretty easy if you use all pcb mounted components.