Augusto Triani, an Italian engineer is actually working on a new Theremin Cello. The first results are very promising, but he admits that there remains still some work to do.
We discussed a little bit together and found that the timbre is actually somewhat too "fluty" and needs more harmonics in order to be more close to the real Cello sound or the sound of the original Theremin Cello.
A demo video (audio only) is available here.
Please post your comments, especially suggestions and encouraging critics here, so that Augusto may lead his creation to perfection with the help of "the community"