Test fixtures have been widely used before the industrial age, including mechanical fixtures, woodworking fixtures, welding fixtures, jewelry fixtures, and other fields. Certain types of jigs are also called "molds" or "assistances", and their main purpose is to reproduce a certain part with repeatability and accuracy. An obvious example is when the key is copied, the original key is usually fixed on the fixture, so that the machine can copy the new key under the guidance of the appearance of the original key.
Test fixtures are produced because of commercial needs, because many types of fixtures are customized, and some are to increase productivity, repeat specific actions, or make work more precise. Because the design of the fixture is basically based on logic, similar fixtures may be produced separately because they are used at different times and places.