A parametric hob, stove, oven, grill, range, volume, potentiometer or rotary encoder knob to fit any rotary actuator with D shape shafts. Size, inside clearance, plunge depth, shaft diameter and most importantly pointer offset angle can all be adjusted to give you perfect satisfaction. Apparently cooker knobs are the "killer app" of 3D printing (acording to wizard23): and as I needed a couple of different sized knobs for missing pieces in rental accomodation, fully parametric was the only way to go! see also http://def-proc.co.uk/blog/a-fully-parametric-hob-knob/Measure your intallation point. You need to know: You should also choose: