Chinlund immediately addressed the most pressing challenge he faced on the film that "jumped" out at him: "How to make all of these characters from so many disparate worlds and visual vocabularies coexist in our world of today. With the Iron Man films, Marvel had been so successful creating a seamless reality where the world felt plausible and even though Iron Man’s tech was otherworldly, it still felt grounded. You could tell how much care had been taken to maintain a truth in the visuals. I felt a tremendous sense of responsibility, to all of the incredibly talented artists and designers who had worked on the films before me, to deliver a world that was balanced and cohesive, and could contain all of these different visual threads."
To do so, he attempted to mix the real world of 2012 with the technologies as represented by Tony Stark and SHIELD, and the attempt was made to represent these ideas as they existed right next to each other.

"That Stark Tower," he says, "was the ultimate representation of this idea, where Tony Stark bought the iconic MetLife Building (formerly the PanAm Building) and ripped off the top, adding his own piece of parasitic architecture to the top. The height of arrogance and the essence of Stark. As a production designer, this was the most rewarding set to design, having grown up in New York and looking at that building everyday throughout my life, to be able to effect its history, forever, was an amazing opportunity. In choosing the MetLife location we were also recognizing the rich topography of the streets below which is a unique arrangement in New York, with the viaduct over 42nd St and the tunnels behind Grand Central Station, not to mention Grand Central itself, the ultimate conflagration of rich histories and futuristic ideas."
The Helicarrier was another impressive achievement for the film. "It was a huge challenge bringing together all of the various ideas and iterations of the Helicarrier that have occurred throughout the Marvel history and creating a cohesive, plausible piece of military hardware that viewers could accept without their suspension of disbelief being pushed off the precipice," Chinlund explains. "I think everyone involved was focused on making this 1,500-foot-long monster battle station look like something could be sailing over Manhattan and not crashing to earth in a ball of badly designed flames. During our research we looked at all sorts of historical, current and conceptual military vehicles, particularly naval vessels — such as the littoral ships — and stealth aircraft, in addition to all of the versions from the Marvel pantheon. We tried to distill from these something that the fans would recognize as the iconic craft and people unfamiliar with the history could accept.

"The bridge of the carrier was the first set we started on, knowing that the ship would need a gathering place for all of the heroes," he adds. "As the main command center of this massive battle station, I knew we would have to deliver a space sufficiently impressive. My biggest fear was that after the first look at the carrier we would wind up in an interior space that didn’t match its majesty. The design for most of the interior spaces was organized around the idea that all of the interior chambers on the ship were suspended from the decks. That the engines were lifting from the deck level and that all of the spaces below were “hanging” from the decks above. This involved an intricate series of pipes and hangers that ran throughout the ship. This helped us develop the architectural signature for the look of the ship. The struts and “ribs” that are seen throughout all reference back to this original idea. On the bridge this idea is most evident in the massive struts on either side of the main viewing window and at the back of the space by the Avengers table."
The creation of the aliens in the film he credits largely to Whedon's imagination and Marvel's ryan Meinerding. "I was tremendously inspired by Ryan’s alien designs," reflects the designer. "I loved the contrasts he developed with the organic materials and the machined technologies. As we were attempting to create the world, I was looking for textures that would allow these beautiful designs to separate from the background and still feel of the world."
For much more, check out the link above.