In saucepan, bring 3 cups water, the vinegar and sugar to a boil; add rice. Cover; simmer over low heat until cooked, 20 minutes. Set aside, covered, for 10 minutes; fluff with fork. Roll into 1 1/2-inch balls; flatten into disks. Using a 2-inch round cookie cutter, cut out salmon; divide among rice disks. Using scissors, cut jack-o’-lantern faces from nori and arrange on salmon.