Roman Numeral D20

thingiverse

I plan to create a custom D20 for my brother, an avid D&D player, with an intriguing roman numeral design. The initial print was satisfactory; however, the bottom portion could improve. The triangular faces appeared concave, and despite a .25 infill setting, the object is nearly 100% solid ABS. For future edits and reprints, I intend to make the model hollow to resolve these issues. Please share any recommendations you may have.