Metallica are busy with their 3D film right now, but guitarist Kirk Hammett says work on their follow-up to 'Death Magnetic' will 'happen soon.'

The guitarist tells Rolling Stone, "Right now, we're kind of preoccupied with dealing with this 3D movie that we shot up in Canada last month. So that's kind of taking our time right now – that's the priority, to deal with that. But once we're done with that, we're going to start hunkering down and putting riffs together. That's all going to happen soon. I really don't have an answer about Rick Rubin, although his name certainly comes up."

In the same interview, Hammett remembers his encounters with Nirvana frontman Kurt Cobain. The guitarist recalls, "He told me that ['Whiplash' was his favorite Metallica song]. He came to one of our shows in Seattle, on the 'Black Album' tour. I remember at one point, we were playing 'Whiplash,' and he looked at me and kept punching the air with his fist and gave me this big thumbs up sign."

Hammett says after seeing the reaction, they dedicated the track to Cobain. The guitarist says, "I knew Kurt kind of well and I hung out with him quite a bit. He was a pretty big Metallica fan - I was surprised at how much of a Metallica fan he was. He loved 'Ride the Lightning.' He loved that album."

While the 3D movie and eventual album work are the primary priorities for Hammett, he's also managing to find some spare time to release his 'Too Much Horror Business' book, detailing his extensive collection of horror memorabilia. The guitarist says, "Over the last five years or so, I started to get a few items that made my collection just that much better. I mean, really raised the overall quality of my collection. I thought, 'I can't be the solitary collector. It's time for me to share it with the world.' So this book is my gift to all the other monster kids and all the other horror nerds out there, who love this stuff as much as I do."

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