#19: Invisible Ink Spy Pens
Can you imagine having the power to write a message somewhere in plain sight that only your chosen few could witness? Such was the appeal of Invisible Ink Spy Pens! Kids could send secret messages to their friends without teachers or parents being able to read them. All you needed was a UV light and the desire for espionage to make your spy dreams a living reality. It’s little wonder that these pens are still on the market today. Being a spy never gets old!
