Ask your non-3d printing friends how it was made, the ball inside is too large to but put in from the outside?
I recommend printing with variable layer height to improve the top/bottom surface of the sphere. Supports not needed with variable layer heights, if your printer can do 20mm (2cm) bridging.
This was a remake of another ball in the box, with with improved printability and no longer needing supports to print, while still keeping the illusion
The author hasn't provided the model origin yet.