The Julia sets
of polynomials z³+c, for c varying along a curve, stacked on top of each other. The curve ends at 0, so the stack ends in a circle and you can use the thing as a fancy little bowl. The polygonal approximations of the Julia sets have been computed for 14 backwards iterations.
Note that the inner contour of the bowl closely follows the outer contour. You can try this version
instead, which has a smooth interior.
For a cheaper version, designed especially with precious metal materials in mind, see here