Our Audi A4 B6 from 2001 lacked the navigation knob located at the center console. So i came up with this one :)

The diameter of the pin on the car is 5,53mm. I had quite a hard time, getting the print to the right dimension and in the end i used a 6mm drill to partially enlarge the hole. Now the knob has a nice tight fit without the need of any glue.