We take an empty diaper box, one end open, and let Isis (the cat) play in it.  Aiden comes along, and starts poking in the box, tormenting the cat.  It doesn’t last long–I think Aiden just lost interest in it.

No.  He comes back 30 seconds later, having taken an egg whisk from the kitchen, and starts trying to extract Isis from the box.  He decided that tools would help.