This shape works very nicely as a 12 sided die, providing an elegant alternative to the regular dodecahedron.
It's is a hexagonal dipyramid, an isohedron
Note that this is a blank, so the faces will need to be numbered. For more information on unique dice shapes, see http://loki3.com/poly/fair-dice.html
1.614 w x
1.614 d x
0.635 w x
0.635 d x