NOTE: this model by itself is incomplete, you must download the addition ground/base pieces from the original source https://www.thingiverse.com/thing:6438369. Specifically, this does NOT contain the surrounding grounds for the base, as I had no need to change those.
The author remixed this model.
This remix has a larger center tube, which is sized at 26mm (to fit larger D20). Also, I added rifling as maybe that would help tumble the dice. In addition, I added holes for magnets (sized 1.75mm x 6mm, which is what I had on hand).