I recently discovered a rotary switch knob that looks just like a miniature version of the inside door handles. It’s the wiper knob for a 47-51 Chevy truck. I added one to my heater blower switch. The style of the knob goes well with both the door handles and the chrome ball knobs on the other dash controls.
The back of the knob is a straight hole designed to fit over a splined shaft, but the shaft on my switch is a half circle type. Fortunately the hole in the knob is slightly smaller than the switch shaft, so I simply carved out the upper half of the hole to provide a tight press fit over the switch shaft and it works perfectly.
The knob is under 6 bucks at Chevy Duty, should you be looking for an interesting addition to your interior.
Here are a few photos with different switch positions to best show the shape:
