We developed a method which allows us to fabricate suspended metallic structures without the need for a sacrificial layer. It consists in the selective dip-coating of a low melting point alloy on etched silicon patterns. The technique was applied to the fabrication of a passive one-shot micro-valve sensitive to the ambient temperature and the input pressure. The working principle of the valve was validated. The primary advantage of the system is its low opening pressure difference (a few to tens of kilopascal).