Pen that writes in metal !

The pen actually functions like a pencil, only instead of leaving behind a trail of graphite, it leaves behind traces of metal when applied to paper. Unlike a pencil, the stuff you write can’t be smudged. The pens are made out of a metal alloy, and it creates lines of alloy when you use it to write or draw.

However, these pens are designed to us so little metal alloy that you can buy one and never run out for the rest of your life! They can also be used to write underwater!