It will provide a familiar smelling, dark, quiet home. A bigger box may be desirable to allow you to see in, as well as to provide plenty of room if you have a mother and a litter of kittens or puppies. Keep several layers in the bottom of the box. They will come in handy when the foster litter starts to roam around the room and into their litter box. The larger the litter, the larger the plate should be, so that no one in the litter gets crowded out.
Some cats have allergies to plastic, so try to avoid plastic dishes.
Provide access to water at all times. Remember, young animals can drown, so make sure the bowl is very shallow. Pet supply store food tends to be more nutritious than grocery store brands. We will tell you if an animal you are fostering needs any other special food. Cats will instinctively use a litterbox and mom will begin teaching her kittens how to use a litterbox.