There’s also the option of connecting a smartphone or tablet to a computer with usb or net. Then running something like touchosc on it. Am dreaming of this plus a car mount next to my midi keyboard on the desk.
Can imagine an xy pad could work well to control theremin like sounds. On the renoise instrument side, with pitch and volume modulation and formula devices to smoothen the modulations everything seems there, just a note has to be triggered and held during performance.
Only questions would be making the plumbing to make renoise receive osc automation with higher than midi 7bit resolution for pitch, and recording such a performance to automation graphs in proper quality.
Interesting. Its true, if the note could be held and the pitch manipulated with as much precision as the theremini, or other moog theremins, to get all those nice vibratos that theremin players do, Clara Rockmore style.
It might be good to have the pitch controlled by a touchscreen fader on touchosc but with twisting a knob on a midi controller in place of a second touch-fader controlling amplitude…maybe it would be possible to set up a theremin-like instrument using two of the knobs on the akai MDP218…to play a nice beat live along to the rest of the song in renoise, then have a crazy theremin style interlude, like a build, before going back into the beat.