In recent years, sustainable design research has increasingly focused on the circular economy, aiming to extend material life and recover materials completely, thereby enhancing material stability. This approach seeks to maintain product value while minimizing waste. Additive manufacturing (AM), also called 3D printing, is recognized for its potential contribution to this paradigm by enabling sustainable materials development. AM facilitates improved manufacturing solutions that align with the circular economy, particularly by encouraging polymer recycling and reuse. However, there is a gap in research exploring this relationship. Addressing this gap, this study introduces a novel biocomposite formulation tailored for extrusion-based 3D printing. The composite utilizes recycled PET from water bottles and biomass waste fillers. Various formulations incorporating biomass and additives were tested for optimal rheological properties and printability. The research demonstrates the potential of the 3D printed recycled composite for applications in automotive, construction, and aerospace industries, aligning with circular economy principles and sustainable manufacturing by utilizing recycled materials in sustainable manufacturing processes.