This went through a few renditions. Originally I printed threads into the center and it was one piece but when the shifter gets hot it starts to get loose which annoyed me. So I decided to make the shifter two pieces with a hex nut spot to make for a tight fit that does not loosen.

Hex nut needed for a Corrado shifter is M12x1.5. The bottom of the shifter has a little lip for the g60 style leather boot to slip over. The Vr6 boot will not work with it but the knob will still fit.

note the best way to join PLA I have found is Sci Grip #4 fast set acrylic liquid*