1. 123 Block. Making these may not be as easy as 1-2-3, but these blocks sure count for many uses in a machine shop! A 1-2-3 block is a piece of steel, ground to a square 1 by 2 by 3 inches and usually drilled with a pattern of threaded holes. It's ideal for setting up machines, inspecting parts, measuring, or simply holding down some paper.