Make a box Out of cardboard
Giving Birth to the Box
Humans have nine months to prepare for the birth of their young, but you might not have any time to prepare your rabbit for her birthing experience. Choosing to go with a cardboard box may be a matter of using what is on hand and easily accessible. Choose a box approximately 12 to 14 inches in diameter. Poke holes in the sides, and cut the front of the box down to 4 inches above ground level. This allows the mother rabbit to move freely in and out of the nest.
Once you have your box, you will need to finish the nest with bedding and straw. In the bottom of the cardboard box, place a 1-inch layer of shavings. A second inch should be added during colder weather. Lay straw on top of the shavings, filling the box completely. You can create a burrow for the rabbit, using your fist to "chisel, " out a small area. You have helped get things started, but don't be surprised if your expectant mother makes her way into the nest and rearranges the entire thing. This is normal.
Wood if You Would
Cardboard is certainly suitable for a nesting box, but there are some downsides. Cardboard will become urine soaked, if it survives that long. Rabbits love to chew, and will gnaw continuously on the cardboard, likely destroying it. Cardboard might be best used temporarily until a wooden box can be fashioned with a metal grate bottom. The cardboard box easily can be slipped inside the wooden box so as not to disturb the nest.
Mom Knows Best
All mothers have a natural inclination to care for their young. Rabbits in the wild leave their nests for long periods, returning only at feeding times. If your little mother doesn't seem to be too interested in her babies, don't worry. She is simply doing what she'd do in the wild. Providing a nesting box, whether it be cardboard or wood, is a good idea, but let your rabbit mom do the rest