Julia Sets and the Mandelbrot Set

Optical Basin Boundaries

Standing between two parallel mirrors in a barber shop does not produce a fractal image. But if the mirrors are round, and if there are enough of them, fractals do appear.
First, assemble the base of the tetrahedron
Now, place the fourth ornament on the top of the base, and look at the gap between the ornaments.
Use folders to differentiate regions by color
Use a laser pointer to investigate the basin boundaries.
Here are some examples from David Sweet's website.
Thanks to Dane Camp for pointing out this excellent example. More detail and some interesting connections are in his paper "Reflecting on Wada basins: some fractals with a twist" in Frame and Mandelbrot.