This controller with no direct antecedents was inspired by recently available conductive, stretchable fabric and a curve known as the witch [sic] of Agnesi.
The fabric is stretched in an embroidery hoop and draped over an inverted circular bowl.
A piece of conductive plastic cut in a special shape forms a corolla on the surface of the bowl. The tips of each petal are folded inside the bowl and taped with conducting adhesive copper tape. The microcontroller board measures the electrical resistances of these petals from their tip to a common center established with a conductor at the flat of the bowl. As the conductive stretchable fabric (the “calyx” to complete the flower analogy) is displaced towards the bowl it shorts out different lengths of each conductive plastic petal.
The result is a circular array of nearly mass-less displacement sensors. The gesture-to-displacement relationship changes according to distance from the center of the bowl (variable “gearing)”. This allows for several different playing styles.
One style, similar to hand drum technique, involves tapping the fabric surface directly onto the bowl with the fingers of one hand and leaning towards the other side of the bowl with the palm.
Another style involves both hands interacting from the outer hoop towards and around the base of the bowl.
You can put it on the ground and use it as multiple foot “pedals”.
The gray fabric is conductive fabric from Eeoynx.