¹ There are a number of commercially available toys which produce interesting, attention-holding patterns of reflected light. Several examples are given in SIS database. Here are a few:

Cheerleader Pompom; Toys-R-Us.

Illuminated Mirror; Avon.

Rotating Diffraction Cube; Rompa.

Spinning Wheel Toy; Rompa.

(For further explanation of SIS, see Appendix II).