The Curta is a mechanical pocket calculator that was popular before electronic pocket calculators rose to prominence in the early 1970s.
The Curta is the brainchild of Curt Herzstark, an Austrian inventor who designed the calculator just prior to WWII. Imprisoned in Buchenwald in 1943, Herzstark received favorable treatment for his technical expertise, and was recruited by the Nazis to assist in the construction of his mechanical calculator, which they had planned to give to Hitler as a gift for winning the war.
Hitler never did get his war victory gift. Buchenwald was liberated in 1945, and Herzstark successfully manufactured his mechanical calculator. Curtas enjoy a resurgence in popularity today, and models in good condition sell for around $1,000.
Yes, Curtas can be 3D-printed, but they are too intricate for home 3D printers to handle at scale; 3:1 versions are more common.
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Mechanical calculator trying to divide by zero