Metal element is base to modern culture in Little Alchemy. There are lots of constructions and combinations need Metal, for example Bullet, Tool, Blade, Train, Gun, Airplane, Armor, Car, and Robot. It is very easy to make Metal in Little Alchemy, you just need to create Lava, Stone, and then Metal. Check out the below instructions and try it yourself.
Earth + Fire = Lava
Air + Lava = Stone
Fire + Stone = Metal