I don't have one because they go for $1000+, but speaking of cylinders, the Curta mechanical calculator is fascinating https://en.wikipedia.org/wiki/Curta http

I don't have one because they go for $1000+, but speaking of cylinders, the Curta mechanical calculator is fascinating https://en.wikipedia.org/wiki/Curta https://en.wikipedia.org/wiki/Curta https://www.youtube.com/watch?v=loI1Kwed8Pk https://www.youtube.com/watch?v=loI1Kwed8Pk