Since you are in NZ, you may be able to get hold of a 3m metre length of these louvres made by an Australian company.
The bottom one AUS8029 is 100mm by 20.4mm. I think it could be used as a mould for the mast.
If you copy the picture and zoom it until it matches the dimensions, it gives an internal width of about 16mm. The 2015 Zeeko carbon mast has a quoted width of 13mm and is compacted carbon fibre.
The idea is that you fill the two small recesses at each end of the mould by pushing small diameter rods into them. You could then maybe use a filler to smooth the nose end of the mast mould.
If you bought 3 m of the louvre, you could cut 1.2m for the layup and split it and use one half to lay the layup on. Lay heat sealable plastic film on the split aluminium to lay the carbon fibre onto.
Then for the wet layup, use 45 degree orientation carbon cloth for wrapping the outside of the layup with maybe unidirectional carbon fiber inside that and possibly a flat polythene tube maybe 2" wide at the core. Maybe like the 2" by 500 gauge polythene lay-flat tube here.http://www.polybags.co.uk/shop/narrow-l ... _c1014.htm
That is a definite 'maybe' as I don't know that this idea could be made to work, but the idea is that you lay up a 1.2m long carbon fibre mast with the tube in the core, then wrap the heat sealable plastic around the layup and heat seal it at the tail side of the mast.
Then slide the whole lot into the louvre with 10cm protruding at each end.
Cut away 10 cm of the polythene wrapper at each end and form them into the top plate and part of the fuselage.
Then inflate the core tube to press the layup against the louvre. It might be best to keep the same underside from the layup when sliding it into the mould, then after inflating it, turn it over to help improve the upperside. It would only be practical to use a low pressure, but it might be enough to press the layup out against the aluminium to give a more compacted part with a better surface. It might help to have drilled very tiny holes in the aluminium to help the air escape.
After it is cured, grind though each edge of the louvre and remove the aluminium.
This is just a suggestion. I don't know if it can be done or how successful it might be.
The idea is to then add the tail edge onto the mast, and build the top plate and fuselage around the existing carbon - blending them to the mast.