Note that this is a PCB only - it is up to you to fabricate a panel and source appropriate components and build the module up.
This is a good beginners project since it only requires a handful of commonly found components and builds up into something that's (hopefully) immediately useful.
This is the first of a new run of my 40106-based drone generator - no real changes from the original design: four channels of the 40106 set up as tunable(ish) oscillators, mashed together using a CMOS logic chip and then output through a Sallen-Key filter. Throw in the current-starve option and sonic wackiness can often ensue.
Use it as a standalone drone generator, as it's capable of producing some fairly dense textures in the right hands, or use it with an envelope generator and a VCA and you've got a source of nice, clashy percussion sounds.
You can find the BOM and panel files here: https://bitbucket.org/yorkmodular/xo106-diy-kit/src/master/