A team of University of Washington researchers has developed a material derived from coffee and mushrooms for 3D printing objects.

Recognizing that coffee is ideal for growing fungus, which forms a "mycelial skin’ that binds loose substances together to create a water-resistant, lightweight material, the team devised a system for turning coffee grounds into a paste that can be used to 3D print objects.

Source: 3D Printing and Additive Manufacturing (2025). DOI: 10.1089/3dp.2023.0342

To develop the “Mycofluid” paste, the team mixed coffee grounds with rice flour, xanthan gum and water. The coffee-based paste was then inoculated with Reishi mushroom spores, which grew on the paste, forming mycelial skin and subsequently turning the coffee grounds into what the team suggests is a fully compostable alternative to plastics.

The team printed an assortment of objects with the Mycofluid, including packaging for a small glass, parts of a vase, two halves of a Moai statue and a two-piece coffin roughly the size of a butterfly. Once printed, those objects were left to sit for 10 days covered in plastic. During that time, the mycelium formed a shell-like substance around the Mycofluid.

The team found that the resulting material was heavier than Styrofoam — more like cardboard or charcoal — but with all compostable parts.

"We're interested in expanding this to other bio-derived materials, such as other forms of food waste," the researchers added. "We want to broadly support this kind of flexible development, not just to provide one solution to this major problem of plastic waste."

The study, “3D-Printed Mycelium Biocomposites: Method for 3D Printing and Growing Fungi-Based Composites,” appears in the journal 3D Printing and Additive Manufacturing.