Those interested in the construction process of curved boards should go look at the DNA A-cat web site. While NACRA may be using an entirely different process, it does give one possible way of building state of the art pre-preg curved carbon boards using autoclave technology. Their molds are made of high temperature composites and appear to be much less complex than those which have been speculated about, on this thread, and others touching on the subject.
DNA is refreshing transparent about their building process. Rather than dodging questions and shrouding their design/construction in ambiguity and mystery, they lay it all out on the table for everyone to see and give their reasoning behind their design decisions.