All three of my kiddos are great at entertaining themselves with everyday household items. Luke, for example, is a big fan of the Tupperware cabinet. After a few times of cleaning up this mess, that cabinet is now locked up tight.
He likes to pull everything out of the cabinet and climb inside. He won't be able to fit in there much longer. Sniff, sniff!
Claire and David are both big fans of the cardboard box. They talked Daddy into cutting windows and doors into this one from our new water heater purchase.
In addition to cabinet climbing, Luke is also a big fan of drawer sitting. (This is at my in-laws' house. He loves their cup drawer.)
All 3 of my kids love playing with laundry baskets. Luke is pulled around in one often.
When the laundry baskets are full (which is all too often in my opinion), you can always find another box of some type to sit in.
Or trap yourself in the laundry basket cage.