Flo Kaufmann used an old vaccum as an enclosure for his analog synth project, the “satrap activ” –
It contains 2 cmos based VCO’s , a Moog ladder filter, a 555 based ADSR, a cmos based 8 step sequencer, a PIC based vc to midi interface and a PIC based auto trigger unit. There are 4 tunable knobs on top, mostly to play base lines, and 2 conductable wires, which act as voltage dividers to generate variable tones. the wires do not vibrate. so it is not a cord instrument. satrap activ can also control other synthesizers either by midi or cv/gate interface.