A pointing machine is a measuring tool used by stone sculptors and woodcarvers to accurately copy plaster, clay or wax sculpture models into wood or stone. In essence the device is a pointing needle that can be set to any position and then fixed. It further consists of brass or stainless steel rods and joints which can be placed into any position and then tightened.
It is not actually a machine; its name is derived from the Italian macchinetta di punta. The invention of the tool has been ascribed to both the French sculptor and medallist Nicolas-Marie Gatteaux (1751–1832) and to the British sculptor John Bacon (1740–1799). It was later perfected by Canova. However, similar devices were used in ancient times, when the copying of Greek sculptures for the Roman market was a large industry.
The pointing machine is used for making one-to-one copies of existing sculptures and to reproduce models made of plaster, modeling clay or modeling wax in materials like stone or wood. It is not possible to use a pointing machine to produce enlarged or reduced copies; the traditional instruments for this are a set of calipers or a three-dimensional version of the pantograph. However, there is also a special version of the pointing machine that was used for mirroring, enlargements or reduced carving.