To mold the musubi, start by placing a strip of nori, rough side up, on a cutting board or clean work surface. Place a Spam musubi maker mold over it, in the middle, then place a slice of Spam into the mold. (If you don’t have a mold, you can line a clean Spam can with plastic wrap instead, and place a slice of Spam at the bottom.) Sprinkle ¼ teaspoon furikake over the Spam, then fill the mold or can with a generous mound of rice. Press the rice firmly with the musubi maker press or with your hands until it is 3/4- to 1-inch thick, adding more rice as needed.