Los Angeles - Metallica are working on a 3D concert film.
The Enter Sandman heavy metal band are in the "very early stages of production" for the self-financed movie, expected to be released in summer next year.
The band said: "There is indeed a 3D project in the very early stages of production! We wish we could tell you more, but we don't have all the finer points nailed down just yet."
Drummer Lars Ulrich added: "We tend to pay for these things ourselves. The minute you take somebody else's money, you have to consider their opinions. And that's no fun."
The group - which also includes vocalist James Hetfield, guitarist Kirk Hammett and bassist Robert Trujillo - originally had reservations about making the film, but were convinced when they found out it will involve the "biggest" live show they have ever performed.
Kirk said: "We didn't want to do it at first. We were sold on it by our managers, that it would be a lot of fun and we would have a big-ass stage to play on - the biggest Metallica live show we've ever done, next-level stuff."
The band are also well into writing the follow-up to 2008's Death Magnetic, working from recordings of jam sessions from their last three years of touring.
Lars explained to Rolling Stone magazine: "We're about seven, eight songs into it. We do it in rounds. We come up with something, we leave it, go to the next thing, come up with something basic, leave it and circle back around."