Reviewed by Lexie CornerFeb 19 2025
Researchers from the University of Washington developed a method to convert nutrient-rich coffee grounds into a paste for 3D printing. The paste is inoculated with Ganoderma lucidum (Reishi) mushroom spores, forming a mycelial network that binds the material. This process produces a compostable, structurally stable material as an alternative to plastics. The study was published in 3D Printing and Additive Manufacturing.
From the upper left to bottom right: the 3D printer creates a design; three printed pieces of a vase; the partially set vase pieces are put together; the mycelium grows on the coffee paste; the vase grows together; the finished vase holds flowers and water. Image Credit: Luo et al./3D Printing and Additive Manufacturing
Only 30 % of a coffee bean's mass is water-soluble, and most brewing methods extract even less. Consequently, of the 1.6 billion pounds of coffee consumed annually in the United States, approximately 1.1 billion pounds of coffee grounds are discarded as waste or composted.
Danli Luo and a research team at the University of Washington developed a method to convert spent coffee grounds into a paste suitable for 3D printing. This material can be used to fabricate objects such as small statues, packaging materials, and vase components. The paste is inoculated with Ganoderma lucidum (Reishi) mushroom spores, which develop into a mycelial layer on the printed objects.
The mycelial network strengthens the material, making it a biodegradable alternative to plastics. Even with complex geometries, the mycelial skin binds the printed structures. Additionally, separate printed components can be fused into a single object through mycelial growth.
We are especially interested in creating systems for people like small businesses owners producing small-batch products—for example, small, delicate glassware that needs resilient packaging to ship. So, we have been working on new material recipes that can replace things like Styrofoam with something more sustainable, and that can be easily customized for small-scale production.
Danli Luo, Study Lead Author, University of Washington
Luo developed the "Mycofluid" paste by combining used coffee grounds, brown rice flour, Ganoderma lucidum (Reishi) mushroom spores, xanthan gum (a common food binder), and water. To facilitate 3D printing with this material, Luo also designed a new printer head for the Jubilee 3D printer, originally developed by the Machine Agency lab at the University of Washington. The modified system can store and extrude up to one liter of Mycofluid.
Using Mycofluid, the team 3D-printed various objects, including a two-piece butterfly-sized coffin, three sections of a vase, two halves of a Moai statue, and packaging for a small glass. The printed objects were then incubated in a plastic container for 10 days, allowing the mycelium to form a cohesive outer layer. The mycelial growth also fused separate printed components into single structures.
The process follows the same principles as homegrown mushroom kits, requiring moisture for the mycelium to develop from the nutrient-rich substrate. If left to grow longer, mushrooms would emerge from the objects; however, the items were removed once the white mycelial skin had fully formed. The pieces were then dried for 24 hours to prevent further fungal growth.
The final material has a density comparable to cardboard or charcoal and is heavier than Styrofoam. It exhibited low water absorption, gaining only 7 % additional weight after one hour of exposure to water, and returned to its original weight upon drying without structural deformation. The material demonstrated mechanical properties similar to expanded polystyrene foam and polystyrene.
While the team did not specifically test compostability, all components of the material are biodegradable and technically edible, though not palatable. Future research will explore other recycled materials that could be used to produce similar biopastes. However, large-scale production of Mycofluid may present challenges due to the need for a consistent supply of uniform used coffee grounds.
We are interested in expanding this to other bio-derived materials, such as other forms of food waste. We want to broadly support this kind of flexible development, not just to provide one solution to this major problem of plastic waste.
Danli Luo, Study Lead Author, University of Washington
Junchao Yang, a master's student at the time of the research, is a co-author of the study. Nadya Peek, an Associate Professor of Human-Centered Design and Engineering at the University of Washington, is the senior author. The study was funded by the National Science Foundation.
Journal Reference:
Luo, D., et al. (2025) 3D-Printed Mycelium Biocomposites: Method for 3D Printing and Growing Fungi-Based Composites. 3D Printing and Additive Manufacturing. doi.org/10.1089/3dp.2023.0342.