Eco-friendly Material that can be Vacuum Formed?

Are there any environmentally-friendly materials that I can put in a vacuum form? We typically use styrene, but I’m looking for something that won’t spend hundreds of years sitting in a landfill. Any help would be great.

I would check out 3-form. I know it is a green material, but it is still a plastic, so it might not be what you are looking for. It might be a start though.