This is in a wholly 2D program. The input is implied to be one completely flat vector drawing, which Illustrator turns into a 3d model, and renders back into flat vectors at multiple rotations, with no further work on the part of the artist.

(I say "implied" because that's all they're showing in the video presentation, there may be additional setup involved that they're skipping. This is inside Illustrator though, which has a long history of 3d extensions being very awkwardly shoved into a corner of its toolset.)