When you download a 3D model from the internet, your computer stores it in the memory module as long lists of numerical values which refer to the coordinates of the model's individual geometric parts.
Such a method of representing a three-dimensional object, however, is not strictly necessary. What if we just let the computer 3D-print a miniature replica of the model and keep it somewhere within its physical space, and then 3D-scan it whenever the model needs to be displayed on the screen?
When a 3D model is supposed to be modified, the only thing the computer will have to do is simply disintegrate its existing replica and then reconstruct the newer version of it at the same exact spot.