Hmmm... maybe you misunderstood. The sheets I meant are already done.
You just saw them to the shape you need and bolt em up
If you want to make big flat sheets yourself, you can use a piece of formica (hope that's the same in English
It's the cheap wood panels with plastic covering)
This will get you a nice smooth surface to work on and it's cheap.
Lay down a good clear gelcoat, then the carbon weave, just like you would with fiberglass
You can make it from different layers of carbon, or just use 1 layer of carbon (the one you see) and use regular fiberglass mats to build up strength/thickness or even kevlar
For curved pieces, the molding is just the same as with fiberglass, except for clear carbon, you need perfect molds and perfect first gelcoat and a nice clean layup to get a good result because all stays visible
With fiberglass, you can fill imperfections because it gets painted anyway
Disclaimer... I've never done this before, but from what I heard and read, this is how it's done...