Another thing I’m supposed to be working on is the construction method for my submodules. These will typically be so-called “dead bug” arrangements of passive components around an op amp chip and maybe one or two of those little 8-legged ATtiny85 MPUs. The idea is that they’ll transform incoming and outgoing signals so that the analogue and digital parts of a hybrid module can concentrate on doing what they do best.
Actually soldering the submodule is easy enough but keeping it electrically and mechanically sound is a job that needs some thought. So far I’ve investigated various potting techniques. I could alternatively enclose each submodule in a small enclosure with protruding wires. Crimping could be involved.