This study investigates the role of 3D printing as a transformative enabler of waste reduction and sustainable inventory management within modern supply chains. Traditional manufacturing systems are dominated by subtractive processes that generate excessive material waste, high energy consumption, and significant environmental burdens. In contrast, additive manufacturing fabricates products layer-by-layer with precise material control, leading to substantial reductions in production waste. The paper explores how 3D printing aligns with circular economy principles by facilitating recycling, reuse, and decentralised on-demand manufacturing. Empirical data, case studies, and visual analyses are used to compare conventional manufacturing systems with 3D printing in terms of waste generation, recycling efficiency, and carbon emissions. Results show that 3D printing achieves significant reductions in material waste, carbon dioxide emissions, and volatile organic compound emissions when compared to traditional production methods. The integration of recycled filaments such as PLA and PET further enhances sustainability by reducing landfill disposal and dependence on virgin materials. The study also highlights the impact of 3D printing on digital inventory and supply chain optimisation. On-demand production minimises overstocking, reduces storage requirements, and lowers transportation-related emissions. The paper concludes that strategic adoption of 3D printing, supported by policy frameworks and technological advancements, can substantially contribute to sustainable manufacturing, waste minimisation, and circular economy implementation in supply chains.