This a complete redesign of https://www.thingiverse.com/thing:4526477/files
The original file did not have a thick enough wall.
The "base" is 6mm, and the ball internal diameter is 2.5" (63.5mm).
The holes to join the two halves together are 6mm.
I was able to print this without supports, with minimal "issues" at the very center.
The author hasn't provided the model origin yet.