Plastic can be made from oil, you don't have to use petroleum, you could use Soy. Well maybe one day it will be around.

Here is a link that might be useful: biodegradable plastic

Konrad I have seen these molds. I think they are terrific fun! Love the little buddahs. They are beautiful! Mrs. G

That's pretty neat! Now to find out where they sell them.

I think this may have been started in Japan with watermelon. The problem is it often (always the case with watermelon) renders the fruit unusable. Many crack and watermelon are usually all rind.
There are many different sizes/shapes etc for sale on Ebay.

Oh...forgot..YES, they are reusable.