Biel, 26, has been romantically involved with Timberlake, 25, since January of last year. Rast is the clothing line that Timberlake and best friend Trace Ayala started in October of 2006.

Jessica, who recently admitted she fears how the onset of time will affect her looks, will reportedly oversee limited-edition handbags for Rast . She's said to be already working on sketches for designs which will debut in the line's next runway shows.

"Jessica is casual when it comes to clothes, but she loves bags," a source says.

Biel and Timberlake have been inseparable lately, most recently attending the wedding of Biel's former 7th Heaven co-star Beverly Mitchell in October in Ravello, Italy and being photographed by paparazzi in cinematic romantic clinches in the streets of Rome.

That's one way to persuade the boyfriend into letting you design his handbags.