This mysterious mask, passed down by the Sheikah, allows the wearer to read the minds of Gossip Stones. The mask is shaped like the emblem of the Sheikah; namely, the eye with a tear. The retrieval of this mask is not mandatory in order to complete either game.
About this papercraft:
You can download this paper model template here: The Legend of Zelda - Mask of Truth Free Papercraft Download