In the short Paperman, what paper product guides the protagonists back to each other?

The answer is Paper Airplanes

In the animated short film "Paperman," paper airplanes are used to guide the protagonists back to each other. The film, produced by Walt Disney Animation Studios, tells a heartwarming story of a chance encounter between a man and a woman in a bustling city, and how they are brought together through the use of paper airplanes. The airplanes serve as a symbolic and magical element that helps connect the two characters in a unique and touching way.