Some lucky Twihard may soon get the chance to own the ultimate in Twilight memorabilia: A perfect mold of Kristen Stewart's rump.

The story behind the butt mold is chronicled in Twilight Forever: The Complete Saga, a new collector's edition of the supernatural trilogy, which comes out tomorrow, November 5. Luckily for us, however, Entertainment Weekly has that fanny-focused featurette.

As the cast and crew explain, the mold was a bit movie magic designed to help Taylor Lautner film scene in Eclipse in which his character, Jacob, carries Kristen's Bella through the forest.

It's only a three-minute scene, but the problem was that the director, David Slade, needed to cover the conversation from many different camera angles.

The solution? A custom-molded seat on wheels, attached to the camera dolly.

"We had a device built because no person could shoot for an entire day carrying someone — even someone as light as Kristen," one of the filmmakers says.

"I literally went and got my rear end molded to make this day easier on Taylor," Kristen recals.

Unfortunately, the device made the scene look unnatural, since Kristen wasn't bouncing at all with each of Taylor's steps. So all the efforts — and the butt mold — were for naught.

"They were like, 'Taylor, can you just carry Kristen for the day?'" Taylor laughs. By the end of the day, my arms are shaking so bad."

The 12-DVD or 10-Blu Ray set includes all three movies, a commemorative photo album, and two hours of never-before-seen bonus content, including this anecdote!

Source: Entertainment Weekly

Dan Clarendon is an assistant editor at Wetpaint Entertainment. Follow him on Twitter and Google+!