Flock paths
An arty thing inspired by the Herschel enneahedron.
The genesis of this was thinking about how to show that the Herschel graph is non-Hamiltonian: there's no path that visits every vertex once.
This simulates flocking gliders, who move between the points on the graph. Because the graph is non-Hamiltonian, every glider is bound to re-visit a vertex before they've completed the tour.