"Metal - you melt it in a big pot again, do the mixture you want to have and pour it into a new form. "

Yes, but the energy spent on producing metals is tremendously higher than making plastic, I did not research but the price on both shows it well. There are nowadays the ideas to stop using fuel and use more wind and sun energy but people not counting all the circumstances. Using recoverable fuel and material sources as algae, grass, wood for fuel could be much more economically and ecologically effective but oil companies will always saying it is a bullshit and you shouldn't even try but always buy and buy...