Modeling a Pair of (Hollow) Slippers in GeoGebra Augmented Reality

[b]Key Question:[/b][br][br]In the screencast below, what part(s) of the surface equations create 2 slippers (vs. just one)? [br]How do we know this to be true?
– Tim Brzezinski

Information: Modeling a Pair of (Hollow) Slippers in GeoGebra Augmented Reality