A new study from researchers Danli Luo, Junchao Yang, and Nadya Peek at the University of Washington reveals an innovative approach to sustainable manufacturing. In their work, the team demonstrates how recycled coffee grounds can be transformed into living biocomposites using 3D printing technology. Instead of relying on petroleum-based plastics, which contribute to environmental waste and depletion of finite resources, the researchers have developed a method that combines digital fabrication with the natural growth of fungal mycelium—a process that not only creates robust materials but also results in a fully compostable product.
Overview of 3D-printed mycelium biocomposite. The mycelium biocomposite paste, Mycofluid, is primarily composed of coffee grounds, can be 3D printed using a hobbyist 3D printer, and serves as the substrate for mycelium growth. Over time, mycelium colonizes the printed structure, bridging small gaps it encounters. This capability enables the creation of intricate geometries, including tall vases with delicate, thin walls. Credit: Danli Luo, Junchao Yang, and Nadya Peek
The essence of the breakthrough lies in the creation of a unique biopaste called “Mycofluid.” This paste is primarily composed of spent espresso coffee grounds, which serve as a recycled base, mixed with brown rice flour to supply essential carbohydrates. Grain spawn, used to inoculate the substrate, and a small amount of xanthan gum ensure that the paste attains a consistent viscosity ideal for extrusion. Water is gradually added to adjust the moisture content until the paste is perfectly tuned for 3D printing. By harnessing these everyday waste materials, the researchers are not only reducing waste but also designing a substrate that naturally promotes fungal growth.
Fungibot consists of a material reservoir (top) that transports biopaste by a motor-driven plunger and an auger extruder (bottom) retrofitted on a desktop motion platform. Credit: Danli Luo, Junchao Yang, and Nadya Peek
To bring Mycofluid to life, the team engineered a custom, open-source 3D printing system known as “Fungibot.” This system is designed to be accessible and cost-effective, built entirely from off-the-shelf components and compatible with standard 3D printers. Fungibot features a material reservoir made from a clear polycarbonate tube that holds up to 1 liter of Mycofluid, and a printhead equipped with an auger-driven mechanism to extrude the paste with precision. The innovation here is twofold: the system dramatically simplifies the process of fabricating complex shapes, and it ensures a steady, consistent flow of material, paving the way for creating intricate, custom-designed objects.
Credit: Danli Luo, Junchao Yang, and Nadya Peek
After printing, the journey of Mycofluid doesn’t end with the deposition of the material. Once the 3D-printed structure is produced, it is placed in a sanitized environment where it receives a daily misting of water. Over a period of about ten days, the living fungal mycelium begins to colonize the printed substrate. This biological colonization not only fuses the layers together but also forms a natural, continuous “skin” over the object. The resulting structure exhibits remarkable properties: it becomes water-repellent, as confirmed by contact angle measurements that reach up to 138°, and its mechanical properties evolve—while the tensile strength decreases slightly, the material becomes more ductile and its ability to absorb compressive forces improves.
Credit: Danli Luo, Junchao Yang, and Nadya Peek
One of the most compelling aspects of this research is the way the living mycelium can bio-weld separate printed parts together. In one striking demonstration, a Moai statue was printed in two halves. Following a week of mycelial growth, the two halves naturally fused into a single, cohesive piece. Similarly, a tall vase was printed in three segments that later merged, highlighting the potential for constructing complex, self-supporting geometries that are difficult, if not impossible, to achieve through conventional molding techniques.
Credit: Danli Luo, Junchao Yang, and Nadya Peek
This study, led by researchers at the University of Washington’s Human-Centered Design and Engineering department, not only provides an eco-friendly alternative to conventional 3D printing materials but also opens up exciting possibilities for the future of sustainable manufacturing. By combining the precision of additive manufacturing with the self-healing, adaptive qualities of living mycelium, the work represents a significant step toward a future where waste is repurposed into robust, biodegradable products. With ongoing research and refinement of the Mycofluid formulation and printing process, this method could soon extend to a wide range of applications—from packaging and architectural components to consumer products—ushering in a new era of sustainable, living materials.
For those interested in exploring the process further, the detailed open-source designs and instructions for Fungibot and Mycofluid are available online, inviting makers and researchers alike to join in on building a greener, more sustainable future.