Our cat was bored being cooped up in the house when it was twenty below zero for a week or so. We built him a play house out of cardboard boxes in which he can tunnel through from one box to another.
We attached the boxes together with packing tape and left some openings in the top for light to shine through and for the cat to enter from above as well as through the side. Boxes can also be stacked on top of one another for a two-story house.
Cats often like to claw on cardboard boxes so the boxes also deter them from clawing furniture.
By Judy S. from Valley City, ND
Check out these photos.
I use cardboard squares, which I cut out of cartons, etc., to put in the corner of the guinea pig cage and also in the ferret cage. These animals usually pick a couple of places to go and go there all the time, making this idea work.