This cat play box is intended to provide the cats with a pastime as well as to prevent them from eating their goodies at once. The cats have to push the rolls to reach the goodies - they can take it out from the top or push it through the breakthroughs of the bottom case.
Just put the goodies inside the box and let the cats try to get it.
You need to print:
1x bottom case
1x top case - print it with face down
6x roll (maybe 7) - print it upright
It should be printable without support, but depending on your configuration you may need some in the breakthroughs of the bottom case and in the deepening of the roll.
Bottom and top case have a snapin-mechanism, so you do not need to screw or glue it together.
As the roll is 2mm smaller than the inner distance of the box (a gap of 1mm on each side) it should roll smoothly. If your printer isn't configured correctly (differences between X, Y and Z lenght) you may get in trouble. I recommend to print one roll and check the size - if needed resize the lenght of the roll.