Convolutions

Camera rotations of clear plastic mouth shields (see bottom) rotating on a turntable and being lit by assorted lights.

These face shields are selling like hot cakes these days but they are developed for the food-service industry, and not suited to replace non-medical masks. They do reflect and refract light in interesting ways though.

From Wikipedia: In mathematics (in particular, functional analysis), convolution is a mathematical operation on two functions that produces a third function that expresses how the shape of one is modified by the other.