Designing A Sustainable Material For 3D Printing With Spent Coffee Grounds

“You can make a lot of things with coffee grounds,” said co-author Michael Rivera of the University of Colorado, Boulder, and the ATLAS Institute, who specializes in digital fabrication and human-computer interactions. “And when you don’t want it anymore, you can throw it back into a coffee grinder and use the grounds to print again. Our vision is that you could just pick up a few things at a supermarket and online and get going.”

As 3D printers have moved into more widespread use, it has sparked concerns about environmental sustainability, from the high energy consumption to the thermoplastics used as a printing material—most commonly polylactic acid (PLA). PLA waste usually ends up in a landfill where it can take as long as 1,000 years to decompose, per Rivera. While there have been efforts to recycle PLA in the same way plastic (PET) soda bottles are typically recycled, it's an energy-intensive process that can't be done by the average user at home. Adding biomass fillers (bamboo or hemp fiber, oyster shells, and yes, spent coffee grounds) makes recycling even more labor and energy intensive.

From the academic paper.

4. 3D PRINTING APPROACH

This section describes our preparation procedure for our spent coffee ground-based material (SCG material), our 3D printer set-up, printing parameters, and our decision process for aspects such as nozzle diameter and print speed.

4.1 Material Preparation

We partnered with a local coffee shop5 to receive their SCG that were previously used to make espresso-based drinks (e.g., lattes, cappuccinos). The obtained grounds were finely ground to approximately Math 1 in diameter (visually similar in size to table salt) and initially wet. We opted to dry the SCG in direct sunlight for two days to avoid energy consumption associated with oven-drying. Once fully dried, we sifted the grounds using a basic kitchen strainer6 to remove any large clumps.

After measuring their proper proportions, all of the dry powders (i.e., SCG, XG, CMC) were combined together in a single jar. The powders were then shaken together for approximately 1 min  to ensure a uniform mixture. This combination was then slowly mixed into another jar containing a proportional amount of water by mass. Once the mixture was homogeneous, the SCG material was loaded into 60 mL syringes7. Following the exact proportions in table 2 produces approximately 90 mL of the SCG material. Notably, this entire procedure can be accomplished in a standard kitchen at home with food-safe ingredients.

Academic Paper can be found at: https://dl.acm.org/doi/fullHtml/10.1145/3563657.3595983