The first electronic hobbyist to take an interest in building computers, whom we know of, was Stephen Gray. In 1966, he founded the Amateur Computer Society (ACS), an organization that existed mainly to produce a series of quarterly newsletters typed and mimeographed by Gray himself.

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Siderian (Wikipedia) The Siderian Period ( /saɪˈdɪəri.ən, sɪ-/; Ancient Greek: σίδηρος, romanized: sídēros, meaning “iron”) is the first geologic period in the Paleoproterozoic Era and lasted from 2500 Ma to 2300 Ma. Instead of being based on stratigraphy, these dates are defined chronometrically.

From ACS to Altair: The Rise of the Hobby Computer (technichistory.com) A certain pattern of technological development recurred many times in the decades around the turn of the twentieth century: a scattered hobby community, tinkering with a new idea, develops it to the point where those hobbyists can sell it as a product. This sets off a frenzy of small entrepreneurial firms, competing to sell to other hobbyists and early adopters. Finally, a handful of firms grow to the point where they can drive down costs through economies of scale and put their smaller competitors out of business. Bicycles, automobiles, airplanes, and radio broadcasting all developed more or less in this way.