London, Jan 10 (IANS): American heavy metal band Metallica are working on a self-financed 3D concert film.

The 3D project is at early stage of production, and is expected to release by summer next year.

"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," contactmusic.com quoted the band as saying.

"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," said drummer Lars Ulric.

The group which also includes vocalist James Hetfield, guitarist Kirk Hammett and bassist Robert Trujillo originally had reservations about making the film.

"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," said Hammett.