Surface plates are actually one of the easiest tools to bootstrap, using the three-surfaces method and lapping with fine grit. The only three surfaces that can

Surface plates are actually one of the easiest tools to bootstrap, using the three-surfaces method and lapping with fine grit. The only three surfaces that can all slide laterally against one another are three perfectly flat surfaces. https://en.m.wikipedia.org/wiki/Surface_plate#History https://en.m.wikipedia.org/wiki/Surface_plate#History Here's a video (four parts) of a guy doing it. He uses modern tools in the video, but really that's just about saving time (and showing off). You can simply subsitute (a whole lot) more time spent lapping for the lathe part in his video. https://www.youtube.com/watch?v=rHmsQEAx16o https://www.youtube.com/watch?v=rHmsQEAx16o