The inner ring of my dimer switch broke, and was looking for an easy fix.

Based on this model for the idea, and this model for the center groove to feed the switch through

The dimensions of the center hole were incorrect in the first model, but I wanted to reuse the outer shell of the original dimmer switch for the aesthetics and not print the second model as is. It merges both solutions and sort-of works as expected, but may not be ideal for heavy use. You will have to glue the piece to the back of the switch as shown in the images.

Hope it helps!