In a blender, combine guava nectar, pineapple juice, and fresh pineapple chunks. Cover and blend until smooth. Divide chopped or sliced fruit among 12 frozen treat molds or 4- to 6-ounce paper cups. Pour blended mixture over the fruit.
Add sticks and cover molds. (Or cover each cup with foil; make a small hole in the foil with a knife and insert a wooden stick into each cup through hole.) Freeze about 4 hours or until firm.