A couple weeks ago I completed a Kaleidoscope of my own design configuration. The reason for building it was that I had some high quality front faced mirrors that had been salvaged out of some kind of copy equipment, and they needed something useful to do, rather than just laying around. The rest of the machine was built from some brass drain pipe, and the gears machined from brass valve stems, and the walnut from left over pieces. Sure, it was work, but now all these things have a useful purpose in life.
The interesting thing, was that in reading some history, I found that the Kaleidoscope was invented by David Brewster in 1816, the same year that Robert Stirling invented the hot air engine. (I've built a bunch of hot air engine models) Both men attended the university of Edinburgh in Scotland, they may have known each other. Although the Kaleidoscope is more or less a toy or object of fascination, David went on and did a lot of research and development with optics, and other fields of science. David was the inventor of the Fresnel lens that was used in light houses all over the world. A very respected gentleman.