You’ll use a self-healing cutting mat primarily with your rotary cutter, but it also protects your table top and has markings that help you measure things. Ideally, you want one that is about the size of your cutting table, but they can get pretty pricey. We suggest you get the biggest one that you can afford. And just a tip from personal experience: When you’re taking your cutting mat home, make sure it is lying completely flat. Don’t leave it in your car on a hot day. Any amount of heat will warp the mat and you’ll never get it back in shape.