This knob fits over at least three rotary light switches that I have tested. One is an architect-style table lamp and the other is a reflector floor lamp. It is designed to allow someone with small, achy or slippery fingers to operate the switch. To install, press the knob on with moderate force. The rotary switch shaft underneath should move down and bounce back up, leaving a small gap between the lamp and the switch. If the knob will not fit over the existing switch knob, or if it spins freely, adjust the socket_gap parameter in the OpenSCAD file. The model is fully parametric, so other dimensions can also be adjusted.

I scoured the thing multiverse and was not able to find such a knob, so I took the opportunity to learn OpenSCAD. I hope it's useful.

It is now available in two sizes: original knob (42mm wide with 8 holds and vents) and medium (32mm wide with 5 holds and no vents).

Print Instructions

I printed it from PolyTerra PLA+ using the default Generic PLA and 0.2mm QUALITY profiles in PrusaSlicer. Check that the top (the flat vented side) is facing down on the print bed so that no supports are necessary.