This interesting shape makes for a unique 6 sided die.
It has a convex hull that's a triangle dipyramid, an isohedron
. Since a triangle dipyramid doesn't have parallel opposite sides, I started from a wireframe. Then I created a shape inside it that has sides parallel to the outside shape.
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
1.974 w x
1.974 d x
0.777 w x
0.777 d x