The very cool and nice Juliette Lewis is almost done working on a feature documentary about her music career and plans to bring the finished film to Sundance next January.

The 38-year-old actress whose credits include “Cape Fear,” “Natural Born Killers,”  “Due Date”and most recently “The Switch” with Jennifer Aniston, began her rock singer career over ten years ago.

Lewis partnered with Chris Maybach and Patrick Cunningham of Maybach Entertainment, producer of “Martha Marcy May Marlene,”  and her manager Brandy Lewis to produce the doc.

“I first heard her sing four years ago when I was at Cannes and I was blown away at how good she is,” Cunningham said in an interview a few weeks ago following the premiere of “Martha Marcy” at the Toronto Film Festival.

Lewis’ career has covered hundreds of gigs, first with Juliette and the Licks and then with the New Romantiques, and she’s performed at festivals in Leeds, Redding, Brazil and on the Warped Tour.

“I knew when I was 28 that I had to keep pushing myself into areas where I felt uncomfortable and exposed,” Lewis said in an interview in Toronto recently. “I’ve always been interested in living dangerously so going into music like this has sort of been my unleashing my love affair with my audiences — a joyful middle finger to the world. I have a real muscular voice that gets compared to AC/DC.”