Nope, but the Mark-8 (1974) was the first microcomputer kit with plans published in a popular magazine. The Mark-8 provided the first big spark that catalyzed the hobbyist movement. Before the Mark-8 appeared, there was at least one hobbyist newsletter, the ACS Newsletter, published by the Amateur Computer Society, which focused primiarily on the PDP-8, the machine which inspired the Mark-8. The Mark-8 spawned a few more hobbyist newsletters, such as Hal Singer's Micro-8 and Hal Chamberlin's The Computer Hobbyist. The machine was designed by Jon Titus. Jon Titus on the Mark-8

Blinkenlights Interview with Jon Titus on the Mark-8

Yet Another Interview with Jon Titus