I started slicing some grocery bags and rolling them out into plarn balls. At random I started crocheting and finally got 27” diameter mat. It’s so soft and pliable and  can be rolled or folded when not in use. Any size can be made depending on how much plastic yarn I have retrieved from the grocery bags. It’s a great environment friendly project to keep the plastic from the landfills. I have one that I am using for the past eight years now!!!