A new modular approach, using Cornish granite, CNC cut copper circuit boards and a lot of magnets.

Theory and rules:

Trying to give a voice to 370 million year old electronic components.
Changing/adjusting the crystal should have a clear result in most circumstances - they need to be in the centre of the circuit, so e.g. taking them away stops the sound.
Specially made cat's whiskers mounted in Cornish granite to make the minerals the focus of a live performance.
Incorporate 1920s crystal wireless technology.
No tuning.

Practice:

PCBs glued to neodymium magnets and can be rearranged inside a repurposed tool box (protects them during travelling/storage).
Extensive use of vactrols.
Sequencing via simple building blocks, binary counters and shift registers.
Syncs with analogue synths via pulse train.
Works well with volca modular.
Inputs/outputs are signal, +4.5V, 0V, -4.5V. Other voltage ranges also work (the diode ladder filter needs at least this much to work).

Modules