Trac-Ball BALL
Made a spare ball for my little cousin's Trac-Ball game, his is blue and difficult to see at times. It's diameter is 3.5" (88.9mm), I used a raft w/ Cura's default settings to prevent it from rolling while printing.
I might try to make the rackets as well, we shall see...
UPDATE: 10/13/2020
Added a "Wiffle ball" style Trac-Ball
UPDATE: 10/24/2020
Tested these today. The standard style (orange ball) is a bit heavier than the original. It flies very well. It can be thrown fast and straight, or it can be thrown high and very far. Definitely pleased with the results.
The Wiffle Ball style (yellow ball) did not have the Wiffle effect I was hoping for, the holes just slow it down and greatly reduce the distance. On the positive view it can be used when space is limited. We concluded that the Wiffle style was more like a "front yard" ball and the original style was for "back yard" and larger spaces, it can be thrown very far.