I made this D20 for a friend. Scale to your liking.

I scaled it to 2.5 inches for my first print and used tree supports. It's a bit tricky, but it's possible to remove all the supports, just be patient and use some needle nose pliers, a scribe, or something long and narrow to fish them all out.

You'll notice around the middle layer that it begins to wobble on one point of contact. I happened to have some luck, but some of the external walls had some layer bubbling due to the top layer curling up. I figure you could mess around with the print orientation to fix this issue, (as you'll need supports anyway) and possibly you could lay it on an edge instead of the 20 sided face. Let me know what works best for you!

I included a STEP file as well as the F3D file I used to make it if you'd like to make some modifications. ( I wish more creators did this ) ; trying to convert an STL to a solid vector-less object is headache-inducing sometimes in Fusion)