Several versions of files describing the Aztec Calendar can be found on the Web. Files are in several formats such Adobe Illustrator format (ai) and others. Some are AutoCad DFX files or even G-Code files ready to send to the CNC router.
The calendar is very intricate and has thousands of three-dimensional shapes. Carving this calendar is a true test for the router. It has to maintain its position to a thousands of an inch or better even after several hundred thousand moves. Note that the CMC machine discussed here has open-ended controls for the axis positioning. The three-dimensional position of the cutter head in space is determined strictly by software. The latter keeps track of the motion steps with a high resolution. Should steps be missed, either by the software or the stepper controllers or should any mechanical part of the drive trains slip, the result would be disastrous.
The picture below shows a rendition by unknown maker.