A slingstone, based off of ancient biconical designs which had excellent aerodynamics. Typical slingstones could be even larger and heavier than this, weighing in at 200 grams at their heaviest. This stone should average out somewhere in the middle of the slingstone size scale, where the smalles sling stones were around 30 grams.
I have set the default material to natural sandstone, for historical accuracy and convenience.
Of course, this small print volume allows you to use whatever material you please. This could be a piece of jewelry, a paperweight, or held up as a work of art.