This is my "Happy Skull" d6 design. It is 24mm on each side (just under 1"), so it is a bit oversized vs. a normal d6 dice. A more standard sized 17mm version is available here: http://www.shapeways.com/model/211715/happy_skull_d6_17mm.html?gid=ug37365 I recommend ordering that one if you're going to print in metal, since i couldn't get this one down to what I consider an "affordable cost" in that medium.
The dice is, despite appearances, reasonably well balanced. Odd numbered sides are opposed by the next-largest even number, and have a single double-thick tooth to help counter-balance the weight of the extra tooth on the even side. Also, each side is rotated 180 degrees from its opposing face. This should put the center of gravity at or very close to the center of the dice, making for a nice, fair roll.