I printed this design originally by Strange_Meadowlark.  It's very good but I kept forgetting how the individual pieces went together. Plus I really liked scaling it up. So I reworked the individual pieces into their component halves. This allowed me to scale it up to 350% on my Prusa i3 MK2S.
The result is this huge d20 that is almost 125mm in diameter.

NOTE: For a smooth finish, be sure to flip the STL file over in your slicer so the numbers print on the bed.

If you scale this up you may have to notch the thick tabs in order to get the pieces to fit together. Remember, mine is 350% scale. You probably won't need to if you print this at a reasonable size.