Dodecahedron.

thingiverse

Perfect Dodecahedron Found. The distribution of numbers that results in the sum of three numbers at each vertex falling between 16 and 23 was discovered. It was also determined that the sum of the numbers on opposite sides is consistently 13. No better allocation exists for this particular dodecahedron, making it an optimal example. You can verify these findings for yourself. One perfect dodecahedron has a series of numbers running along its edge.