We received requests for double amputees with two partial upper limbs. There is an instrument called Santoor, it uses two wooden sticks "Mezrab" to tap on strings. It does not require complex hand movements or fingers, provides an opportunity for amputees to be able to play this instrument.
We started a project a while ago but the tests haven't been perfect enough to upload on the website as a finished prototype.
We can easily connect to the arm or the tip of their silicon rubber prosthetic.
Please share ideas and comments below. This should be an interesting subject to work on.