What was the first computer mouse made of?

Answer

Douglas Engelbart's 1964 prototype had a wooden shell.

Context

Engelbart's team at the Stanford Research Institute built the first mouse prototype in fall 1964. It had a single button and was housed in a carved wooden block. Two wheels, one turning horizontally and one vertically, tracked motion across the desk; this meant it could report movement along two axes without any ball or optics. The device was operated with one hand, which let a user keep the other on a keyboard.

Engelbart filed the patent in 1967 as an 'X-Y position indicator for a display system' and it was granted in 1970 as US 3,541,541. The name 'mouse' came from the cable trailing out of the back, resembling a tail, though nobody recalls exactly who first used it, and Engelbart himself said it simply stuck.

A frequent claim credits engineer Bill English with building it. The Engelbart Institute notes that a draftsman drew the specifications and the SRI machine shop built the device. The mouse became widely known through Engelbart's 1968 demonstration in San Francisco, which used a later model with three buttons, not the wooden original. Commercial adoption came decades later with the Xerox Star in 1981 and Apple's Lisa and Macintosh in the 1980s, after ball-based designs replaced the wheel mechanism. The Smithsonian holds a replica of the first prototype.