Rothy’s The Flat 7.5W Maritime Blue Knit Ballet Shoes Knit from Rothy’s signature thread, which is spun from plastic bottles. Learn more. It took about 11 plastic bottles to knit this pair of shoes. In 2023, Rothy’s factory achieved TRUE Platinum certification, validating that it’s operating with Zero Waste Practices by diverting solid waste from landfill, incineration and the environment.