Things You'll Need
Utility knife or box cutter
Between hand ripping and machines made specifically to accomplish the task, shredding paper is extremely easy. Cardboard is thicker, harder to hand rip into small pieces and too tough for most shredders. Shredding cardboard can be an effective way of recycling it and allows for a few home uses, including as lining for composting, weed control mulch for gardening or bedding for pets. While some shredders are big and strong enough to handle cardboard, most home machines are not, so cardboard needs to be shredded by hand without leading to severe pain.
Make the cardboard as flat as possible. If it's still in the form of a box, break off the sides. Rip or cut the folds and overlaps using a utility knife or box cutter to make the surface of the cardboard smoother and less likely to cause jumps during cutting.
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Wet the cardboard. This makes it softer and easier to cut.
Lay the cardboard down flat on a cutting board or other hard surface that won't be damaged by having the paper cut on top of it.
Cut the cardboard into strips using the utility knife or box cutter. Strips can be as thick or thin as convenient or wanted. Thinner strips will take longer and require more effort, but make for softer pet bedding and better mulch. Cutting along the corrugations makes the task much easier.
Rip the strips into smaller pieces.