A kittening box is the enclosure in which a cat will give birth to kittens. As such, the box needs to be safe, hygienic and warm. Most cats prefer a dark, warm and quiet environment. The kittening box should be stored in an area that is away from most of the activity in the house. Most kittening boxes are made from pet carriers or sturdy cardboard boxes. If using a cardboard box, make sure it has a removable lid.
Select a strong cardboard box with a lid. Legal or letter boxes, the kinds used in offices, are perfect. They have strong, removable lids and are study enough to carry heavy papers. The sides should be 20 to 30 inches high. The box should be able to fit the cat comfortably lying down; if the box can fit two cats comfortably then it is definitely big enough.
Clean out the box. Make sure any dust, dirt or objects have been removed from the box. Wiping it down with a slightly damp paper towel will grab fine dust.
Cut a hole on one side of the box. The hole should be 5 inches wide and the lowest point of the hole should be around 5 inches from the ground. The higher hole will prevent the kittens from crawling out, while still allowing the mother to leave. The hole can extend all the way to the top of the box.
Line the bottom of the box with several layers of newspaper and paper towels. The cat will cut these materials up to make its own nest. Replace the lining every day after the kittens are born because the paper will be soiled. Replace the lining more frequently, if necessary.
Select a location for the box. A warm room, that is dark and quiet is ideal. Introduce the box to the cat several weeks before the expected delivery. Once a location is selected, place the cat in front of the box and hope the cat will chose the box for her nest.