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You can use it to explore the operating principle of the Curta, zoom in on every part and perform actual calculations.
To view the model you need a VRML viewer: a plug-in for your operating system that allows you to view the Curta, and other VRML worlds.
Installing the recommended browser is free and automatic. I does not expire, but a little logo floats trough the scene. Just ignore it. It helps if you imagine that its a flying saucer with aliens looking at the amazing Curta too!