Gib Bogle wrote: > Can you imagine a symmetrical 5-sided 3D shape? I can't.
Not with five planar faces, but you needn't limit yourself to those. Take, for example, five copies of the "rounded lozenge" defined in the plane by
5/6 - sqrt(1-x^2) < y < sqrt(1-x^2) - 5/6
and make them the curved faces of a banana-shaped die. I'd even trust the six-sided version of this more than I'd trust a regular die -- I've never understood how to spin the usual design in a way that doesn't appear to favor some faces over others, but with this design you can obviously just spin it around the axis of n-fold symmetry.
You could also use a gamer's d10 with the faces labeled with two copies of the digits 1 through 5, or an icosahedron labeled with four copies. A dreidel would also work -- that strikes me as the fairest design of them all.