Nest Boxes and Hammocks
Rats need places to sleep. Most rats will sleep in either enclosures such as boxes and igloos or hammocks.

Igloos and Boxes
A nest box can be created by putting a small cardboard box into the cage. Tissue boxes work well. Make sure there are no tapes, glues or plastics on the boxes that you put in. Generally boxes will only last about a week or two before they get shredded.

If you want a more permanent solution you can get a plastic igloo in most pet stores. They work well and are pretty resistant to chewing. Make sure to thoroughly wash the igloo at least once a week.

Igloo

Hammock

Hammocks
Hammocks are a must for rats. They love laying suspended in the air. You can find a large variety of expensive hammocks in pet stores. They're usually found in the ferret section.

I prefer to make my own using old hand towels. The towels are cheap and they're a lot easier to wash than the store bought hammocks. To attach the home made hammock just use normal safety pins.


Hammock
Hammock