I've played around with the idea of an all carbon fiber marker for a few weeks now. I don't know if its ever been tried before or even suggested. It sounds like it would be a extremely difficult build, however i believe it is possible. My experience with the stuff doesn't extend beyond making some brackets for use in robotic applications.
like he said, carbon fiber threads = bad idea. Otherwise it should be cool. The problem is milling carbon fiber. carbon fiber is milled with carbide and diamond tipped cutters at 30,000 - 40,000 rpm. my advice would be to make something 95% carbon fiber and use aluminum inserts for threaded holes and what not.
Lover of All Things Paintball
Not sure if I'm correct about cs900's reasons for the project, but I assume he tried/accomplished his project purely for the challenge of doing something that hasn't been done before. To see if it could be done. To have a marker that uses as little metal as possible. And everything beyond that is a plus.
I think it would be a good idea to use metal inserts, kind of like ram sleves, and wrap the fiber around them to make the gun. That way you don't have to worry about the cf wearing and fraying. And you might also be able to use a 3D waterjet to mill it, but don't take my word for it.
personally I'm thinking (and will more than likely be doing) that you should take a regular body and mill the outside as THIN as possible, then carbon fiber the outside of the sucker. Thus you have a threaded, sealed carbon marker.
Are you talking the frame and everything else would actually be made of carbon fiber. I know that sounds like a dumb question. But i ask because i have seen plenty of marker where they just appear to look like carbon fiber but its just a hydrodip