This is a cat toy ball with a simple design that's quick to print. My first foray into similar toy balls required a lot of support material. This one consists of two domes that friction-fit together with pegs. The size -- slightly smaller than most similar commercially-sold cat toy balls -- and the mostly-closed-off design are loosely based on an existing cat toy that my kitties are partial to, except that one is held with glue, not pegs.

Use it as-is, put a jingle bell inside (as I did -- rescued from a previously stepped on cat toy), or hide a catnip sachet inside (an empty tea bag works well).

For those wanting to get into OpenSCAD, I have included the *.scad source code, although it's not trivial, it's well partitioned into functions, uses reasonable variable/constant names, and isn't too difficult to follow.