In 1943 License plate were made of soy composite,what is this?

Question

They were made of a soy composite to conserve on metal for the war, what is a soy composite made up of, and how long would they last?

Answer 1

These plates were a failure. Farmers reported having their pick up truck plates eaten by livestock when they parked their truck where livestock could approach. Others reported animals in the wild did the same.

I am not sure exactly what was made and it was not repeated in the next year.

Answer 2

My guess is forever. It is a plastic that was made from soybeans + some other ingrediants. Henry Ford made a prototype with a body that was made out this stuff.