Parameterized shifter knob for Jeep automatic transmission

I was getting tired of the Tee style shifter in my Jeep TJ so I decided to make a cool new one. I made everything parametric so it may be modified for different applications. If you have questions comment below but here are the basics....

All measurements are in mm. Measure DIAMETER, not radius! The diameter is already cut in half by the code.

1. First determine how big you want your knob. Input this as knobdiameter. 55 is pretty comfortable and looks beefy.
2. Second determine how