As with some other cancelled conventions recently, the Robocon convention that was supposed to be re-introducing us to BotCon for next year, has posted online 120 odd images that are concept sketches, colour guides, and mould/tooling layouts.

Most are of Armada toys, but there is one interesting concept design that is said to be a "Metroplex" playset for the 2007 movie. The design looks very 1980s, so was either a really early concept for the 2007 movie, or was easily dismissed for not being able to blend in to the Movie toyline.
(it also must mean that Metroplex must have been an option for Michael Bay to use in his movies, but never went that way)