This is the through-hole reincarnation of one of my old modules, the MDM (Modular Drum Machine) - I call it a crap-fi module because, let's face it, the sounds that you'll get out of it are rough, ready and pretty characterful.
The board features:
Note that this isn't an ideal beginner's kit, although if you're patient and can hold a soldering iron at the right end then you can do it.
BOM and schematic can be found here: https://bitbucket.org/yorkmodular/mdm2/src/master/
Approximate board size: 78x100mm - it will fit behind a 16HP panel