You can choose from several alternatives, including using a layer of plastic wrap over a thick (sturdy) tea towel (kitchen towel). However, if you’re new to making homemade sushi, I recommend purchasing a bamboo mat (they’re inexpensive!), as they’re the easiest way to roll tight, uniform sushi rolls. Alternatively, you can use a tool called a "sushi bazooka." Place the rice and filling in the machine, and then push it out of the machine into a ready-formed roll. You can then wrap that with a nori sheet.