I want to make a flat sheet (or rather block) of carbon fiber that is 3cm thick? It's not a big block, roughly 7x7cm. I can only imagine infusion would be pretty useless for this as vacuum will have hard time pushing down that thick of a sheet so I'm thinking wet lay up and put something really really have on top to compress. What say you? Also, most importantly, how many layers do you think i'm gonna need to build that kind of thickness?

With regards to the weight point, I think you're right Warren, but I was thinking more in terms of strenght vs. weight in a complex shape, and as it turns out thats exactly what "StanTheMan" wants to carve out of his CF block.. 

personally I would make the watch case as a "forged carbon" part..  I.e., shredded CF with Resin stuffed into a metal mold, and precision cut pieces of very fine weave prepreg CF for the top and bottom layers.

Use high pressure "workshop hydraulic press" and heat the mold with an oil heating system.

I'm working on such a setup to make CF / Carbon Nanotube rifle-scope mounts.  They will have molded in threaded Titanium studs for the assembly screws..

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