This is interesting. I was told from a composite expert that one could
fashion the shape of a complex manifold using sections of hotwired blue foam
initially appearing as a blue foam pipe.  The pipe is cut into setions and
glued together and sanded to shape.  The whole thing is coated with silcone
seal and layed up with glass.  disolve the foam with solvent and pull out
the silicone with pliers.  It is supposed to leave a smooth surface.  I Have
never done this but it could work.

Hendersonville, TN.
RV9 N658RP Reserved
If nothing changes
Nothing changes