Used cooking oils are a major global environmental problem, with commercial and household waste causing serious environmental issues, including clogged sewage lines caused by the build-up of fats. While there are commercial uses for waste cooking oil, there’s a lack of ways to recycle it into a high-value commodity.

With that in mind, researchers at the University of Toronto Scarborough have, for the first time, turned waste cooking oil – from the deep fryers of a local McDonald’s – into a high-resolution, biodegradable 3D printing resin. Using waste cooking oil for 3D printing has significant potential. Not only is it cheaper to make, but the plastics made from it also break down naturally unlike conventional 3D printing resins.

The team of researchers used a straightforward one-step chemical process in the lab, using about one liter of used cooking oil to make 420 milliliters of resin. The resin was then used to print a plastic butterfly that showed features down to 100 micrometers and was structurally and thermally stable, meaning it wouldn’t crumble or melt above room temperature.

Conventional high-resolution resins can cost upwards of $525 per liter because they’re derived from fossil fuels and require several steps to produce, but this new process that uses old cooking oil can create resin at just $300 per liter, which is cheaper than most plastics. It also cures solid in sunlight, opening up the possibility of pouring it as liquid and forming the structure on a work site.

Add in the fact that this resin is biodegradable, and it seems these researchers have come up with a groundbreaking process that could make 3D printing greener while eliminating a huge source of waste.