I suppose your talking about making the sensors pickup in some sort of Cartesian coordinate pickup pattern…like the Kaoss pad uses the X-Y planes. Unfortunately, in the Altura’s case you can’t really cross the sensors because they will interact with each other, based on what i was saying earlier about the sensors being ultrasonic technology rather than optical.
Historically, 2 hands were used with Theremins because controlling pitch and volume need to be independent of each other. I don’t think it would be too easy to try it with one hand. Besides the circuitry would have been very difficult to design with the analog components they had 90 years ago when the Theremin was invented.
-Brach