Cube sides, flapping and sliding
Started with a vague vision of some kind of elegant geometric choreography. By the end, it just kept making me think of flies buzzing around an overly-accommodating cube. Graceful, synchronized flies.
Interesting (?) Mathy note: The paths of the spheres/flies was originally modeled as and , causing them to reach the edge of the cube at . However, the path didn't sweep far enough outside the box to make the animation work. The path was modified to and , which allowed the spheres/flies to still reach the edges at those same t values but sweep a larger arc outside the cube.