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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 rotation

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.

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1. A method of incorporating a preformed shape into a rotational molded product, the method comprising: 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) a

1. A method of incorporating a preformed shape into a rotational molded product, the method comprising: 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 charge 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 along with the second resin. 2. The method of claim 1, wherein during positioning step b), the preformed shape is retained in a desired position against the inside wall of the rotational mold by tabs, metal inserts, threads, magnets, undercuts, glue, tabs or clamps on the wall of the rotational mold. 3. The method of claim 1, wherein the preformed shape is a translucent sight window, the second resin is opaque and the product is a tank for holding gas, water or other fluid. 4. The method of claim 1, wherein the second resin charge is calculated to an amount necessary to adhere and entirely cover an exposed interior surface of the rotational mold. 5. The method of claim 1, wherein the first resin is in the form particles of a powder, micro-pellet or pellet. 6. The method of claim 1, wherein the rotational mold has a metal surface and the second resin is more attracted to the metal surface of the rotational mold than the preformed shape and wherein said second resin builds up on the metal surface when heated and only binds to the perimeter edges of the preformed shape. 7. The method of claim 1, wherein after the step of heating and rotating the rotational mold to form the rotational molded product, adding one or more additional resin layers by rotational molding to cover the preformed shape and second resin. 8. The method of claim 7, wherein the first resin is translucent, the second resin is opaque and the one or more additional resin layers are translucent. 9. The method of claim 1, wherein said first and second resins are rotational mold resins. 10. The method of claim 9, wherein the rotational mold resins are selected from polymer resin, linear polyethylene resin, a cross-linkable polyethylene resin, ethylene vinyl acetate, thermoplastic elastomer, poly lactic acid, acrylic, vinyl, polyester compounds, nylon or composites of various rotationally moldable materials. 11. The method of claim 1, wherein the preformed shape is a sight window, tab, shaped indicia, colored indicia, mounting tab, object with preformed hole, threads, small detailed feature, solid features, object with localized properties. 12. The method of claim 11, wherein when the preformed shape is a sight window, the first resin is translucent when cured. 13. The method of claim 1, wherein the uncured preformed shape is formed by sintering. 14. The method of claim 13, wherein the sintering of the first resin into preformed shape is conducted by pressure sintering, heat sintering and/or laser sintering, and wherein the sintering does not substantially transform the nature of the resin from a powdered, micro-pellet or pellet consistency and the first resin is kept below its curing point or crosslink activation point. 15. The method of claim 13, wherein the preformed shape is sintered onto a carrier. 16. The preformed shape of claim 15, wherein a thermal conductivity of the carrier relative to a thermal conductivity of the rotational mold is chosen so that the first resin and the second resin melt at the same rate during the step of heating the rotational mold. 17. The method of claim 1, wherein the uncured preformed shape is formed by melting the first resin without curing the first resin. 18. The method of claim 17, wherein the first resin is a crosslinkable polymer and crosslinking of the first resin has not occurred. 19. The method of claim 18, wherein peroxide in the crosslinkable polymer has not been thermally activated and crosslink bonds have not formed in the polymer. 20. The method of claim 17, wherein the first resin is a linear polymer and wherein gas bubbles still remain in the preformed shape. 21. The method of claim 17, wherein the preformed shape is formed by rotational molding or hot press and then cut, milled or stamped into a desired size and dimension. 22. A method of incorporating a preformed shape into a rotational molded product, the method comprising: a) sintering to form a first resin into an uncured preformed shape having perimeter edges; b) positioning and retaining 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. 23. The method of claim 22, wherein during the sintering step, heat and force is applied to compress the first resin into a desired preformed shape and thickness. 24. The method of claim 22, wherein the sintering of the first resin into the preformed shape is conducted by heating the polymer above its melting point without completely curing the polymer. 25. A method of incorporating a preformed shape into a rotational molded product, the method comprising: a) melting to form 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.