Lollipop by God's Box.
A design I approximated with the help of some German synth enthusiasts (an interesting convo only made possible through the magic of Google Translate).
There's two 100+ nF capacitors on the initial PCB that have a 0805 footprint, but should ideally be a class 1 dielectric. I've only found 0805 class 1 capacitors up to 47 nF, so this either needs some kludge or a general indifference for this kind of thing (it's in an envelope circuit so not really critical). The BOM already shows a larger footprint for these.
In the first PCB version I was unsure about one connection, which is left open as some solder bridges. This needs to go to 'GND', not 'FET'.