This is not an incredibly complex programming project per se, but there are many nuances we can create in the behaviors; The interaction between the distance of the viewer and an analog synth (along with other physical reactions, however the synth is at the core). Much conversation needed to get there! 
Interaction between the Arduino and analog synth will be done with Midi which will be converted to Control Voltages via this unit: A-190.
I feel it is a little beyond my current skills to get the details right so seeking a collaborator. This is a paid gig.
Thanks!
Evan