a 500 ml Al can weights 13 grams. life knows if we can skim down its weight if we don't have self openers, the price if we develop a better recycling system etc

a 500 ml Al can weights 13 grams. life knows if we can skim down its weight if we don't have self openers, the price if we develop a better recycling system etc. if plastics have impact on human health, how many $ we can save for using re-usable glass and metal?