3D scanning permits you to create a digital model from a physical object. The process is appealing because it can be difficult to create computer models of complex shapes. Recreating an existing part from scratch, even with a computer, is like copying a printed page by retyping it. Although 3D scanners are not as straightforward as a photocopy machine, the intent is the same.
Whole body scanner from Cyberware
You can render and print a digitized model to communicate shape information, extract dimensions from it to show size information, and use the 3D database to manufacture a replica using additive fabrication or CNC machining. You can also include the 3D model in a video clip as a learning tool or assembly aid.