An existing lab-scale experimental setup system, originally developed for a patented Rapid Rotational Foam Molding (RRFM) process, was re-designed, built, and its functionality was successfully experimentally verified. The primary objective of the research work presented in this thesis was to provide the physical means to introduce a physical blowing agent (PBA) into RRFM processing operations in order to enable seamless processing of functionally graded polyethylene foamed composites. The quality of the produced specimen were assessed in terms of:​ foam density, volume expansion ratio, cell density, and cell size. The experimentally obtained rotationally molded foam composites desirably exhibited gradual change in compositional quality and morphology from one region to another, which was correlated with the thermal gradient that exist within the rotational mold during the part cooling process. The newly designed functionally graded cellular composites can have wide applications in automotive, aerospace and marine industries.