Woodworkers have brass setup bars for precision setup — machinists have gauge blocks. You stack a series of gauge blocks to match the desired measurement, for accurately checking and setting measurements and calibrating instruments.
Precision-milled from super-hard carbide steel, each of the 36 blocks contained in the pictured SAE gauge block set measures 1-3/8″ high by 3/8″ long by its specified width. The set includes blocks 0.05″, 0.10″, 0.1001″ to 0.1009″ by 0.0001″, 0.101″ to 0.109″ by 0.001″, 0.110″ to 0.190″ by 0.01″, 0.20″ to 0.50″ by 0.10″, 1.00″, 2.00″, and 4.00″ wide in a custom wood case.
A calibration certificate included with the set certifies it to be grade B at 68°F, which should be suitable for workshop use. This set of gauge blocks will run you $70 — we don’t even want to know what a grade A set runs.