There is another documented relay computer - RC-3 built in Goodwill Computer Museum.

It is a clone of Harry Porter’s relay computer. Here is the description of the computer from the site: “The RC-3 is an 8-bit computer with a 16-bit address bus that uses 418 electromechanical relays as logic elements. It has 421 lights and 134 switches on its front panel, and runs at the blinding speed of 6 Hz. It was designed and built by the founders of the Museum of Computer Culture during the 2010-2011 timeframe, when they were volunteers at Goodwill Computer Museum.”