Rational Molding Process
Rational molding differs from all other plastic processing methods in that the heating melting, shaping and cooling stages after all occur after the plastic is placed in the mold and no external pressure is applied during forming.
This has the advantage that Roto Molded products are essentially stress free. Large products can be produced very economically , mold costs are relatively low and designers have more freedom with regard to shape.
Most colors can be introduced by Utilizing pigments to achieve different colored products.