We recently bought a child's foldable play pen (For our dachhsund who injured her back, who is completely confined for a atleast a month while she heals) and as soon as I took it out of the box, and placed the box on the floor...the kitties claimed it as their own! I keep large boxes for cats, and i use small boxes for my rats and hamsters.
boxes are a favorite around here.. Tabbi will try to squeeze herself into any box that she thinks she will fit in.
When she was younger, I once found her in an empty 12-can pop carton. I showed it to my (now ex) hubby, and told him that cats are easy to please, and he insisted that I put her in there.
James had bought a new desk chair over the summer.. the cats claimed the box as soon as it was empty.. we let it sit out for them to play with for about 6 months or so, they had eventually clawed it up enough that it wasnt much of a box anymore.
My aya gets all excited when I'm opening a delivery from Amazon.jp now. I'm not sure if its the sound of ripping plastic and paper, or that she knows she gets a new box to chew on and push around for a couple days.