Just fill this food-grade flexible ice tray with water or any kind of juice, and freeze Silicone Silicone is a lightweight material with rubber-like qualities made from a pure form of very fine sand. Halloween Skull & Bone Crossbones Ice Cube Chocolate Soap Tray Mold Silicone Party maker.Not only is it heat-resistant but you can also use it in the fridge, freezer and microwave, which means that it has great versatility - think molding frozen desserts among other uses.