[SIGCIS-Members] question about DIY computing in the 1940s/1950s

While writing about the National Bureau of Standards' SEAC tonight, I began to wonder: what are some other examples of computers in the late 1940s and early 1950s that were developed by customers because it was easier than buying one commercially? I'm specifically interested in machines that were completed and put into real-world use, not those which were experiments.