Blech also means sheet metal. So a metal (beverage) can is a Blechdose (a Dose is a can). Colloquially one could also say "Red kein Blech" which literally translates to "Say no sheet metal" and means "Stop saying nonsense" or something among those things.

If a sound is blechern we are speaking of a tinny sound. It can also be used as a verb: blechen stands for paying, typically used for when someone has to pay too much or for bad reasons (e.g. when they gave you a ticket for parking in the wrong spot).