Here are a number of plane curves, epicycloids, made three dimensional by extending them along the z axis as was done for the pentagram in thing:209452 - Star Ornaments from Pentagrams. A hole for hanging allows a mobile to be constructed.

Depending on input parameters the epicycloid can have 1 cusp, the cardioid, 2 cusps, the nephroid, 3, 4, 5, 6, etc. cusps, becoming a circle as the number of cusps approaches infinity. Six examples of output from the openSCAD code are included, many more are possible.

Stl files are:

cardioid_mark_1.stl
nephroid_mark_2.stl
epicycloid_mark_3.stl
epicycloid_mark_4.stl
epicycloid_mark_5.stl
epicycloid_mark_6.stl

The openSCAD code constructs both double sided and single sided versions of the curves. Single sided versions are given here as the double sided versions are more difficult to print. The examples shown in the image above are the result of gluing two single sided prints together.

The single sided files can be printed directly on the build surface.