We present six rotary knobs, each with a distinct shape, that provide haptic force feedback on rotation. The knob shapes were evaluated in relation to twelve haptic feedback stimuli. The stimuli were designed as a combination of the most relevant perceptual parameters of force feedback; acceleration, friction, detent amplitude and spacing. The results indicate that there is a relationship between the shape of a knob and its haptic feedback. The perceived functionality can be dynamically altered by changing its shape and haptic feedback. This work serves as basis for the design of dynamic interface controls that can adapt their shape and haptic feel to the content that is controlled. In our demonstration, we show the six distinct knobs shapes with the different haptic feedback stimuli. Attendees can experience the interaction with the different knob shapes in relation the stimuli and design stimuli with a graphical editor.