A 1-2-3 block is a machinist’s tool that woodworker Stephen Evans uses every day in his shop. It’s a 1-in. x 2-in. x 3-in. block that has perfectly square sides with sharp corners, ideal for simple layout and setup. Use it to check for square, to true up saw blades and to do lots of other tasks. Search online for “1-2-3 blocks.” A set of two costs about $34.