How a solid glass prism kaleidoscope reflects by total internal reflection with no mirrors, what Brewster wrote about it in 1819, and its limits.

How coloured glass is worked for kaleidoscope wheels: cut sheet glass, kiln-fused glass, lampwork, frit and stringers, and what each does to the image.

What dichroic glass is, how thin-film interference splits light into a transmitted and a reflected colour, and how it behaves in a kaleidoscope.