What functional item made Tom a wealthy inventor in "Made of Honor"?

In “Made of Honor,” Tom became wealthy by inventing take-out coffee cup collars—the cardboard sleeves wrapped around hot disposable cups.

The 2008 romantic comedy establishes that Tom Bailey earns royalties from the invention, reportedly receiving a dime every time one is used. That income explains how he can live as a wealthy New York bachelor without holding a conventional job.

The item is also commonly called a coffee collar, coffee sleeve, cup sleeve, or cup holder sleeve. These terms refer to the same basic heat-protective accessory, so “Take-Out Coffee Cup Collars” is the canonical answer for the film’s joke and premise. It is not a coffee lid, a reusable travel mug, or the cup itself.

The invention is introduced in the film’s backstory after Tom and Hannah meet at Cornell during a Halloween party in 1998. Ten years later, Tom’s financial success from the humble coffee accessory contrasts with his initially carefree lifestyle and sets up the movie’s romantic conflict.