I've got a whole series of vehicles that I'm looking forward to restoring, customizing and building from scratch. Being a former autobody mechanic, (now a home garage tinkerer), I've seen many frame machines up close, but have never actually worked on a surface plate, which is probably the "golden standard" for anybody who is absolutely serious about building a straight chassis and body. Although I've built many of my shop's tools from scratch including a rotisserie, I'm lacking the knowledge about the key essentials to building a surface plate. I see some on the web being four posts with longitudinal rails, and two plates running the length of the frame. Others look to be solid 1/2 inch plate steel, much as a table top. Which is preferred, and why? Better yet: what have you seen, or what do you use?