Seems this little puzzle shows up in different configurations from time to time. This time was my turn. I picked the two oldest versions to credit for this remix. These were the two puzzles that provided the inspiration for these two updated versions of the same puzzle.
Okay, that said, I added a couple of things to these great puzzles...
First of all, these don't fall apart when thrown or spun.
I added a small detente in the mating parts just to maintain the solved puzzle. This also means you have a little more work to do to get it open again.
The second upgrade is the internal pocket for a prize, surprise, token, or what have you. The token can be 3/4 inch cube or a 1" sphere in size. If nothing else, add a marble to the puzzle and really make it interesting for your cat.
Last but certainly not least, I've added clearances where print issues have a tendency to cause interference.
I've tested this in PLA (wht) and ABS (gry). ABS does require sidewalks but PLA should be ready to use right off the build plate. Please note that I've published the STL files as mirrored pairs. If you want them as single pieces, just remove one in Mesh Mixer. Bottom line, you need 6 pieces to make the puzzle. Supports should not be necessary if your printer can manage 45 degree overhangs.
The puzzle is based on a 60mm sphere. Clearance is 1/2mm between mating faces. Once solved, it should be a fairly loose fit. Solving this puzzle should not require Herculean efforts. Dexterity is certainly a plus.