The problem with using carbon fiber for a jig is the carbon fiber has an excellent affinity for glue, particularly CA, but other glues stick extremely well. This means when it is time to REMOVE said carbon fiber a single errant drop of glue means that at least one rib will break, probably more.
Use drill rod. A little candle wax rubbed on before threading the ribs on means most glue won't even stick.
Speedymetals is reasonably priced.
Phil