The intense competition challenged many of the city's architectural firms to build elaborate structures with notoriously fickle materials. "When it comes to the gingerbread, it's really about the bragging rights," said Mat Wolff,associate director of the American Institute of Architects Houston. [...] in its eighth year, the event has grown to attract as many as 4,000 spectators eager to watch a holiday hobby executed with professional skill. The firm had produced a precise rendering of the scene, but the challenge was building the parts to scale in the frenzy of the moment, said Samantha Peters, an architectural intern with the firm. On a bench nearby, Jason Benitez's cold fingers worked an X-Acto knife into a thick slab of gingerbread that would eventually support a castle inspired by "Game of Thrones."