shape tech 2

found a knob I like_____420610017..._
           '/Y_/'              \
         .P' /"-----''''''''''''+
         |   /                  |
        .' _/                   |
   _,..<'::/                    -+.
   +-'''. /     . . . .... . . `|,'
    \._   '                     ,/
     '----...............------"

has a seam, it's a cast resin that's been sanded and worked a bit, 2 set screws.
it's indicator is a curved cutout that gives a surprising kind of precision in the suddenness of wiping the graduations. (like how distortion/folder circuits bring out hidden interior aspects of the sounds?)
Research into properties of variations on the curve of the cutout. relationship to lensed skirts I've seen?

anyone know about this knob? who made them, material, process..