BLACK SABBATH's Tony Iommi and QUEEN's Brian May are said to be planning a collaborative album that will allow fans to build their own songs around the musicians' unused material.Iommi lifted the curtain on the rockers' secret project in the latest issue of Kerrang! magazine, in which a number of fellow musicians pose questions to the QUEEN axeman. Iommi asked, "When are we going to get to work on that album of riffs together? You know what I'm talking about…" May replied: "Yes, I do know what he's talking about and I'm very, very keen. The record he's talking about was supposed to be a secret but I guess he's blown it now!" He explained that on visiting Iommi's studio, he was struck by the amount of unused material the BLACK SABBATH guitarist had. "I thought it would be great to make a compilation out of them," May said. "The idea was to put all these riffs out in some form so that people could build their own songs from them. You could make your own music with Tony Iommi on guitar!"