A CAD 3D file of an eternity rope ring is a digital design file that contains all the necessary information to produce a physical version of the ring using a 3D printer. The eternity rope ring design features a continuous loop of twisted rope, symbolizing eternal love or friendship. This type of file is typically used by jewelers or designers who want to produce unique and customizable jewelry pieces. The file can be modified to adjust the size, shape, and other details of the ring before printing, allowing for a truly personalized end product.