It’s so easy to make, you may want one for every room.
Here’s what you’ll need:
-4 ply or thicker yarn
-K size or smaller crochet hook
-Plastic grocery store bag
-A heaping tablespoon of catnip

Instructions on making circles simply specifies a 10” diameter, does not give specific pattern. For example, you could use this pattern :
(http://comfortforcritters.org/files/documents/Blanket-in-...)

or this pattern (http://comfortforcritters.org/files/documents/Pet-bed-pat...) without the sides.