Lots of people use those plastic easter egg things (the hollow kind that open). If he has a favourite treat you can hid it in the easter egg and leave it open a crack or you can take it apart completely and hide treats under the egg halves. I've recently been hiding about half of Quigley's dinner under them around the cage. Also Quigley really loves cardboard egg cartons I open it and put it upside down it makes a nice tunnel to crawl through or sleep under. He will also walk around with a half dozen egg carton on his back. Occasionally he flips it over and sits on top of it.