A coordinate-measuring machine (CMM) is one way of 3D scanning.
- "Robot Arm Type": here a human guides a 'finger' of a device that looks like a robot arm over a model or sculpture. This deals well with overhangs and precise geometries like boreholes or outer diameters. Coordinate Measuring Machines, or CMMs are often built in this configuration.
- "Generic Touch Probe": we can mount a touch probe toolhead on a 2+1 axis machine like a CNC router, mill, or RepRap. This is convenient if we don't have a robot arm handy.