We're showing a lot of restraint by not just typing "IT'S A TRAP!" in all caps here.
The man beneath that Admiral Ackbar costume is none other than Mythbuster and friend of Geekosystem Adam Savage. Having top-notch fabrication skills and access to some of the best special effects minds around is bound to help one's cosplay game, but seriously, this is some next-level stuff. Savage showed off his costume on the floor of San Diego Comic Con and outlined its creation on Tested.