Craft projects to make using Disappearing Ink Pens

Invisible ink, also known as security ink, is a substance used for writing, which is invisible either on application or soon thereafter, and can later be made visible by some means. Invisible ink is one form of steganography, and it has been used in espionage. Other uses include anti-counterfeiting, property marking, hand stamping for readmission, fun children's games, and marking for the purpo... From Wikipedia