In a 10- to 12-inch frying pan over medium heat, stir sesame seed, sunflower seed, pecans, and almonds until sesame seed is pale gold, about 3 minutes. Add coconut and stir until sesame seed and coconut are golden, about 2 minutes. Stir in cereal and cranberries. Remove from heat.
Meanwhile, in a 5- to 6-quart pan, combine peanut butter, 2 tablespoons butter, and marshmallows. Stir often over low heat until marshmallows melt and mixture is smooth, about 5 minutes.
Add cereal mixture and mix quickly to coat evenly. Pour into a buttered 9- by 13-inch pan or dish. Cover with foil and, using pot holders to protect your hands, press firmly to make an even layer. At once, peel off foil.
Cool or chill until mixture is set. Cut into 24 bars, each about 1 1/2 by 3 inches. Serve, or store airtight at room temperature up to 3 days.