What has been discussed so far would be cedar core. I am guessing that they would be hand made as the guy who I have spoken to is James Jarvey (JJ Boats, make stuff like scorpions, very pimp wood boats). He makes all our glass sheathed racing foils for the Osprey and Kestrel so he knows what he is doing.
If people are interested I will look into getting them CNC cut as that would be far easier I would have thought.