This paper investigates the feasibility of using mycelium colonization to upcycle household waste, specifically cat litter and spent coffee grounds, into large-scale screening elements through 3D printing and toolpath-informed design. The study introduces a composite that repurposes cat litter, a household waste that is typically sent directly to landfill, as a substrate for fungal growth within additively manufactured forms. By eliminating casting molds and employing continuous fractal toolpaths, the fabrication approach reduces secondary material waste while enabling space-filling, intricate geometries with parametrically controlled spacing that supports mycelium growth. This process extends existing biofabrication precedents through increasing geometric complexity. The research develops a repeatable workflow integrating material circularity, mycelium colonization, 3D printing, and computational fractal design to support scalable biofabrication. Prototypes were produced and evaluated at three incremental scales: 9 cm, 15.24 cm, and 22.86 cm. This work contributes to the biodesign community by demonstrating a resource-efficient method for transforming cat litter into biodegradable screening panels within a circular material system.