Playing with imperfect alignments, a small displacement,
rotation or difference in period to make interference patterns
occur that lead to the impression
of a three-dimensional effect.
Moiré patterns are not really there; they are an optical illusion created in the image in your eye.
A slight motion in one of the objects creates large-scale changes in the moiré pattern.
These patterns can be used to demonstrate wave interference, but also the illusion of a three-dimensional depth in the relationship between human, object and motion.