A puzzle-sculpture in three parts.  The pieces are 3D prints in steel/bronze composite metal, and they interlock with 3/8" spheres.  It's held together by the inverse of tensegrity: compression forces hold the balls in place.

This piece ships with one set of balls in neoprene rubber and another set in frosted glass, which are pretty but a bit trickier to manage.
 

Moon Pi, 3" diameter

This piece is no longer in production.