Google said it had started using recycled plastic in Chromecast devices in an interview with Fast Company and used plastic bottles to make the fabric on Google Homes and cases. The move follows the green initiative of Apple to use recycled materials in its products, with the company going so far as to make an in-house robot disassembling old parts hardware. Samsung also announced a comparable commitment earlier this year, promising to use sustainable materials in its product packaging.
If you want to participate, Google currently has a partnership recycling program that will provide you with a shipping label to send devices that you no longer need to Google. Currently the program is limited to the US.