This study examines functionally graded materials (FGM) on a polymer based large scale additive manufacturing system. FGM utilizes a less expensive material with sub-optimal mechanical properties for the majority of the part, and uses more expensive higher performance material in selected areas. This process aims to optimize cost with weight and mechanical performance. FGM is already used a variety of industries, but is not common place in additive manufacturing, specifically large scale additive manufacturing like Cincinnati Incorporated’s Big Area Additive Manufacturing (BAAM). BAAM can use a variety of plastic injection molding and extrusion style polymer pellets, which allows it to use both commodity materials and high performance engineering polymers. This study is an initial assessment of FGM using glass fiber reinforced ABS and carbon fiber reinforced ABS, and characterizes the performance of a density gradient shape function to characterize the blending of materials.