We dump around 8 million tons of plastic trash in the oceans each year, and that might quadruple in a decade. Now, as giant ocean cleanup devices start to sweep through the water in an attempt to collect some of that plastic, a handful of companies are figuring out how to use it to make new products–like shoes.

In June, Adidas released a design for a new sneaker with an upper knit from ocean plastic. Now the design has gone a step further, with a midsole that’s 3-D printed from the same material.

The ultimate goal is a shoe that’s 100% trash, and the company is almost there. “We’re close,” says Eric Liedkte, Adidas Group executive board member of global brands. It’s part of the company’s overall sustainability strategy.

“We’re always thinking about reducing our carbon footprint, and we’re continuously thinking of ways to reduce our use of virgin plastic,” he says. “We are partnering with Parley to save the oceans because we must stop waiting, we must start acting, and we must start somewhere. There is no better and more important place to start then with the oceans. They are the sustenance of all life and they are dying.”

Ocean plastic–like the illegal gill nets that Adidas is collecting via a nonprofit called Sea Shepherd–isn’t necessarily easy to work with. The company is still working with researchers at a German university to tweak the midsole. “It took a lot of hard work and persistence to get the right mixture of ocean plastic materials,” Liedkte says. “We are still working to make it fully functional.”

They plan to release the world’s first shoe with an ocean plastic upper in a limited release in 2016. The company also plans to start building the trash into other products, like clothing.

“The ambition is to continue to innovate to help athletes while looking at every way possible to do less harm. … While we will not compromise on the integrity of our innovations for the sake of sustainability efforts, we will look to build sustainability into every innovation,” he says. “3-D printing is a great example. There is no real reason all 3-D printed product in the future is not made out of ocean plastic.”