An optical toy in a tube; it produces symmetrical patterns as bits of colored glass are reflected by mirrors WordNet 3.0 & Open English WordNet

A kaleidoscope is an optical instrument with two or more reflecting surfaces tilted to each other at an angle, so that one or more objects on one end of these mirrors are shown as a regular symmetrical pattern when viewed from the other end, due to repeated reflection. Wikipedia

Tube of mirrors containing small colored objects. Wikipedia Disambiguation

Optical instrument published in the patent Wikidata

A cylinder with mirrors containing loose, colored objects such as beads or pebbles and bits of glass. OmegaWiki

A tube of mirrors containing loose coloured beads etc. that is rotated to produce a succession of symmetrical designs. Wiktionary

Tube of mirrors rotated to produce symmetrical designs. Wiktionary (translation)