The accelerated rate of technological progress in 3D printing has transformed various sectors like aerospace, medicine, construction, and consumer products. The key to such progress is the variety of feedstock materials, whose selection has a bearing on mechanical properties, printability, and sustainability of the final product. This paper highlights the need for adopting secondary resources like recycled polymer, metal waste, industrial wastes, and bio-based materials as feasible feedstock for additive manufacturing. The important discussion continues into emerging areas like up-cycled materials, high-performance composites, and bio-based printing materials, and then presents a discussion of challenges related to cost, availability, and reliability to reduce carbon foot prints. This article discusses innovative methods for incorporating waste-derived materials like recycled plastics and bio-based filaments for stimulating a circular economy for 3D printing.