Researchers from the University of Colorado at Boulder (CU Boulder) are using spent coffee grounds to help reduce waste from 3D printing.

Using a paste of spent coffee grounds, water and other sustainable ingredients, the team developed an approach for 3D printing a range of objects including craft jewelry, pots for plants and espresso cups, for example.

Flower planters 3D printed from used coffee grounds. Source: Michael Rivera

As a substitute for the thermoplastics used in 3D printing — most commonly polylactic acid, or PLA — the team turned to coffee to avoid the accumulation of PLA in landfills where the material could take up to 1,000 years to decompose.

As such, the researchers mixed water, dried coffee grounds and cellulose gum and xanthan gum, which are both common additives in food that easily degrade in a compost bin, to create a substance that resembles the consistency of peanut butter.

Once dried and extruded, the substance is reportedly as tough as unreinforced concrete, that when dropped will, so far, not break, the researchers explained.

The CU Boulder team has created small planters out of the coffee ground mixture, where seedlings for plants like tomatoes can be grown. Once they grow tall enough, the plants can be planted — pot and all — in the soil.

Further, the researchers added activated charcoal to spent grounds to create components capable of conducting electricity — for instance, buttons for sustainable electronics.

An article detailing the process, “Designing a Sustainable Material for 3D Printing with Spent Coffee Grounds,” was recently presented at the Proceedings of the 2023 ACM Designing Interactive Systems Conference (2023) held in Pittsburgh, Pennsylvania.

For more information on the process, watch the accompanying video that appears courtesy of CU Boulder.