And don't forget the boxes the toys came in.
How about empty 12 pack boxes? My ex and his brother would get drunk and walk around wearing them on their heads. They called themselves the "Schaffer Bros"...you know, after that crappy 2.98 per 12 pack beer? I came across a pic of my son wearing a Budweiser 18 pack box sitting next to his uncle, who of course was lit like a Christmas tree, laughing his ass off.
The boxes take more imagination that the toys that come in them. My dad was a mailman. He also loved to scavenge. One day he brought home these huge pieces of styrofoam, and I built a fort out of them :)