Was about to order a shift knob and it occurred to me that I should at least have a go at printing one. Many prototypes later, I've posted up the current version to Thingiverse here:
https://www.thingiverse.com/thing:3170820
Requires a multi-material printer and a bit of finishing work to get it like the picture, but nothing exotic if you're already into 3D printing. Ends up heavy and I think it looks pretty nice finished -- the pic below is of an earlier but serviceable prototype. And it doesn't use a whole lot of material to print.
https://www.thingiverse.com/thing:3170820
Requires a multi-material printer and a bit of finishing work to get it like the picture, but nothing exotic if you're already into 3D printing. Ends up heavy and I think it looks pretty nice finished -- the pic below is of an earlier but serviceable prototype. And it doesn't use a whole lot of material to print.