Hamsters, gerbils and other small rodent pets are easily and cheaply entertained. A cardboard tube or two placed inside a cage provides endless entertainment for furry friends who enjoy running through tunnels. As an added bonus, the tubes also double as chew toys!
Larger animals, such as rabbits, reap the same joy out of cardboard boxes with a couple of holes cut in the side. This concept can even be taken a step further by attaching multiple boxes and cardboard tubes to create an elaborate pet playhouse. Downloadable cardboard cat toy templates are also available on the Web and include instructions on how to make a cardboard mouse or ball that Fluffy will enjoy chasing for hours [source: Marmalade Pet Care].