The essential parts of a kaleidoscope are a transparent glass “dome” with a colored pattern adhering to its flat base and a metal plate almost as large as the base of the dome with a loop or (rarely) a pinshank inserted. The loop shank does not enter the glass. Most kaleidoscopes measure small, a few are medium size. Most are round, a few are oval or shell-shape.
Many on my card show wear , click on image to enlarge