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.
It is speculative but plausible to guess that the 1965 release of the PDP-8 might have instigated Gray’s own home computer project and the later creation of the ACS.