Explored environmental impacts of materials inoculated with mycelium in contrast with petroleum-based thermoplastic filaments to drive sustainability of 3D printing. Petroleum-based thermoplastics designed for cradle-to-grave processes presented an opportunity for a local, bio-based, renewable, compostable feedstock alternative to be developed and provide a more sustainable solution to bypass petroleum-based feedstock problems in Fused Deposition Modeling (FDM) process technology. Results showed the research, development, and test of a native fungus-based paste recipe for paste extrusion was feasible using a Micro 3D printer. Native fungi spores were inoculated on the host paste material to demonstrate metabolic processes of the mycelium root structure and results showed fungus spores can derive from a liquid bacterial culture. Finally, Life Cycle Assessment (LCA) results showed a mycelium-based feedstock improves the total life cycle impact per category versus the commonly used acrylonitrile butadiene styrene (ABS) feedstock. The life cycle scenario was scored using ReCiPe Endpoint H methodology to combine multiple impact categories.