[[Pre-production]] began around August 2008, with Del Toro, Jackson, Walsh, and [[Philippa Boyens]] writing the scripts. Del Toro collaborated with Jackson, Walsh and Boyens via [[videoconferencing]], and flew every three weeks, back and forth from [[Los Angeles, California]] (where some of the designs were done) to New Zealand to visit them. Del Toro spent his mornings writing, and afternoons looking at material related to Tolkien to help him understand the writer's work. He watched [[World War I]] documentaries and examined Jackson's memorabilia about the war, including working reproductions of planes, tanks, cannons, ships and uniforms. Del Toro felt Tolkien's experiences in that war impacted his stories.
By November 2008, every week Del Toro, Jackson, Walsh and Boyens would realise something new about the story which continually changed the script. The writing hours increased to twelve each day, as they dedicated three weeks to finally deciding the films' structures. Filming will take place throughout 2010 in New Zealand, and Del Toro will renovate the [[Hobbiton]] sets in [[Matamata]]. On his part, Jackson has kept the [[Rivendell]] scale model and the [[Bag End]] set (which he has used as a [[Guest house (secondary suite)|guest house]]) from the trilogy. During the middle of the shoot, there will be a break which will allow Del Toro to edit ''The Hobbit'' while sets are altered for the second film. The director expected the shoot to last 370 days.
During the first few months of 2009, writing would start from 8:30 am and end at 3 pm when Del Toro would meet with Weta. Completion of the story outlines and treatments ended in March 2009, and the studios approved the start of writing the screenplay.
Del Toro interprets ''The Hobbit'' as being set in a "world that is slightly more golden at the beginning, a very innocent environment" and the film would need to "tak[e] you from a time of more purity to a darker reality throughout the film, but [in a manner] in the spirit of the book". He perceives the main themes as loss of innocence, which he likened to the experience of England [[Aftermath of World War I|after World War I]], and greed, which he says [[Smaug]] and [[Thorin Oakenshield]] represent. [[Bilbo Baggins]] reaffirms his personal morality during the story's third act as he encounters Smaug and the Dwarves' greed. He added "The humble, sort of a sturdy moral fibre that Bilbo has very much represents the idea that Tolkien had about the little [[English people|English]] man, the average English man", and the relationship between Bilbo and Thorin would be the heart of the films. The [[Elf (Middle-earth)|Elves]] will also be less solemn.
Del Toro met concept artists [[John Howe]] and [[Alan Lee]], [[Weta Workshop]] head [[Richard Taylor (movies)|Richard Taylor]] and make-up artist Gino Acevedo to keep continuity with the previous films, and he will also hire European comic book artists to complement Howe's and Lee's style on the trilogy. He hopes [[Mike Mignola]] and concept artist [[Wayne Barlowe]] can help the project for a few weeks. He has also considered looking at Tolkien's drawings and using elements of those not used in the trilogy.
As Tolkien did not originally intend for [[One Ring|the magic ring Bilbo finds]] to be the all-powerful talisman of evil it is revealed to be in ''The Lord of the Rings'', Del Toro will address its different nature in the story, but not so much as to draw away from the story's spirit. Each [[Dwarf (Middle-earth)|Dwarf]] will need to look different from each other.Del Toro will redesign the [[Orc (Middle-earth)#Adaptations|Goblins]] and [[Warg#Tolkien.27s_Wargs|Wargs]] and the [[Mirkwood]] spiders will also look different from [[Shelob]]. Del Toro felt the Wargs had to be changed because "the classical incarnation of the demonic wolf in [[Norse mythology|Nordic mythology]] is not a [[hyena]]-shaped creature".
Del Toro also wants the animals to speak so Smaug's speech will not be incongruous, though he explained portraying the talking animals will be more about showing people can understand them. Smaug will not have a "snub [[Simian]] [mouth] in order to achieve a dubious lip-synch", and Del Toro notes that such is the attention given to him that he will be the first design begun and the last to be approved. The director, whose [[Chinese zodiac|Chinese zodiac sign]] is the [[Dragon (zodiac)|Dragon]], is fascinated by the mythological species and attempted to include one in ''[[Pan's Labyrinth]]'', but was unable to for budget reasons. His favourite cinematic dragons are [[Maleficent]] in ''[[Sleeping Beauty (1959 film)|Sleeping Beauty]]'' and Vermithrax Pejorative from ''[[Dragonslayer]]''. He has also provided a foreword to Howe's portfolio book ''Forging Dragons'', where he discussed the dragon's differing symbolism and roles in various cultures and legends.
[[Ian McKellen]] and [[Andy Serkis]] (who played [[Gandalf]] and [[Gollum]], respectively), have met Del Toro, and ideally, he wants every actor (including [[Ian Holm]], who played Bilbo in ''Rings'') to reprise their roles, although he acknowledged some may be unable to because of health problems; he would also consider having Holm narrate the films. All 13 Dwarves and [[Beorn]] will appear, while Thorin's father [[Thráin II]] will also feature. [[Doug Jones (actor)|Doug Jones]]—who portrayed various creatures in ''[[Hellboy (film)|Hellboy]]'', its [[Hellboy II: The Golden Army|sequel]] and ''[[Pan's Labyrinth]]'' was interested in playing [[Thranduil]], King of Mirkwood and [[Legolas]]' father, but del Toro said he wanted Jones for a different role.Similarly, Hellboy star [[Ron Perlman]] is a person whom del Toro has "something in mind for".
Del Toro and Jackson have a positive working relationship, where they will compromise on disagreements to the benefit of the film. Del Toro believes he will be able to shoot all of the films himself, although Jackson noted he had similar hopes for filming all of his trilogy, and has offered to help as [[second unit]] director. Del Toro will shoot the films in the trilogy's 2.35:1 [[Aspect ratio (image)|aspect ratio]], rather than his signature 1.85:1 ratio. He hopes to collaborate again with cinematographer [[Guillermo Navarro]]. Del Toro shares Jackson's passion for scale models and background paintings, though he wants to increase the use of [[animatronics]]; "We really want to take the state-of-the-art animatronics and take a leap ten years into the future with the technology we will develop for the creatures in the movie. We have every intention to do for animatronics and special effects what the other films did for [[virtual reality]]."Spectral Motion (''Hellboy'', ''[[Fantastic Four (film series)|Fantastic Four]]'') are among those Del Toro wants to work with again. Some characters will be created by mixing [[computer-generated imagery]] with animatronics, and some will solely be created with animatronics or animation. Gollum will be entirely digital again, as Del Toro noted "if it ain't broke, why fix it?"
Del Toro and Jackson considered the sudden introduction to [[Bard the Bowman]] and Bilbo being unconscious during the [[Battle of the Five Armies]] to be "less cinematic moments" reminiscent of the novel's more "fairy tale world" than ''The Lord of the Rings'', which they would change to make ''The Hobbit'' feel more like the trilogy. However, Del Toro considered some of these moments like Bilbo waking up to find the battle is over iconic and would require the "fairy tale logic [to] work as is".