The secrets to how Benedict Cumberbatch was transformed into the fearsome dragon Smaug in The Hobbit have been revealed in behind-the-scenes footage included on the Desolation of Smaug Extended Edition Blu-Ray, set for release on November 3. In the new clips, the British actor is seen donning a motion-capture suit, writhing around on the floor and speaking to Bilbo.

Benedict CumberbatchBenedict Cumberbatch starred alongside Martin Freeman (sort of) in The Desolation of Smaug

"We wanted someone who would something original, unexpected," director Peter Jackson says in the clip, "Something that was a surprise to us."

The Weta Digital animation team - those behind Smaug - told the Hollywood Reporter that Cumberbatch's head movements and expressions helped to create a rounded Smaug. Though none of the actor's motion capture was actually used in the big-grossing movie, the movements were used as a visual reference to inform the mannerisms of the character. 

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In a separate report from the Hollywood Reporter this week, the total cost of The Hobbit films is now nearly $745 million. According to financial documents filed in New Zealand this month, Jackson's movies - made in a never-before-seen frame rate of 48 frames per second and shot in 3D - cost three times as much as the The Lord Of The Rings trilogy. However, the gamble (if it ever as a gamble) has paid off to the tune of $2 billion in global box-office receipts. 

More: read our full review of The Hobbit: The Desolation of Smaug

Jackson shot the films back to back in New Zealand and reportedly had enough material to convince studio Warner Bros that a trilogy was a good idea. The first film, An Unexpected Journey grossed over $1 billion worldwide, while Desolation of Smaug took $958 million. The third movie, The Hobbit: The Battle of Five Armies, hits theaters on December 17, 2014. 

More: More Bard than Bilbo? What to expect from The Battle of Five Armies