Simply, a speaker (for any electronic source, example Axoloti) without a speaker cone.
I have tried the prototype a couple of times, different locations, from small to bigger rooms, (example studio in IRCAM to main Auditorium at Superbooth18) connected with many electronic instruments and was always a very rewarding experience, not only sonically but also sensory when it is in direct contact (ONDES+playing instrument)
Its still in countdown... but I can't wait!! to have a bit of the acoustic world closer.