Some call it Madcap. Others, Zany. Over here it is called Screwball, because it is two halves of a ball that screw together.

Print. Screw halves together. Repeat.

The ball is suitable as a container for other smaller balls, or anything really. I put water in it and it leaked a little bit, but not too bad.

No supports needed. I printed it on a Replicator 2 in PLA and a Replicator 2X in ABS and both worked fine.

Parameterized Autodesk Inventor file included, so you can mess with all the attributes.