A method of incorporating a preformed shape into a rotational molded product by a method that comprises the steps of a) forming a first resin into an uncured preformed shape having perimeter edges; b) positioning the uncured preformed shape having perimeter edges against an inside wall of a rotational mold; c) adding a second resin into the rotational mold; heating and rotating the rotational mold to form the rotational molded product, wherein said second resin binds to the perimeter edges of the preformed shape and the preformed shape becomes cured. The invention also relates to a rotationally molded product that has a preformed shape made of a first resin incorporated into an object or vessel made of a second resin, wherein the preformed shape is integral with the object or vessel.