This is a Rhombic Dodecahedron with side length 22mm and a max distance of 50.8mm.

It is printed on a single edge, giving all sides a similar texture. 

If you are having trouble with the shape coming off the baseplate try a bit of glue and/or sinking the corner into the baseplate a bit. However I have printed 6+ in various filaments without issue.

I'd recommend a matte black filament, but I printed the one in the pictures with a prusament gold PLA.