Print on it's side with supports on the shaft, this will give it strength. 3 walls, 50% gyroid infill.
Optionally, give it some fuzzy skin on what will be the top surface.

The concave variant is superior, IMO. I also like it with a shorter shaft, as pictured in the cover photo.

Cut the shaft short if you'd like. Can do this before or after printing.
Shaft is 4mm sides, if you just want to make your own.