The air duct is manufactured from pre-preg graphite woven cloth which is placed in a mold and then vaccuum baggged and placed in a kiln or autoclave. The shape of the mold determines the shape of the part - carbon/ epoxy structures are very, very rigid and also somewhat brittle. Also, be aware that there are many galvanic-couple issues to deal with when carbon comes in contact with steel, or especially aluminum. Unless you have some composite structure fabrication experience, i'd suggest leaving this to the pros.