This project is in development... just received physical boards from pcbway.com. The first shows my intentions from a more or less theoretical + trial-and-error vantage point.

The second shows my first (happy!) attempt to implement my idea. As with everything I do, there's plenty of room to learn and improve, but I'm having lots of fun with reed switches in this one:

This also shows a kind of crossover with my "Twelvey" voltage controller project (https://hackaday.io/project/171644-twelvey-cv-interface-for-modular-synth).

More details, including a schematic, are on their way soon.