What I was thinking about is a little different from machining a wood core and then vacuum bagging or molding a skin over it.

The idea started years ago when I saw an exotic piece of furniture built like this. With this method the structure was built into the "block". First the skeleton was bonded to gather in a jig. Long, short, and little blocks of wood, composite and even steel was joined to form the structure. Then the outer wood that will be seen was bonded to the structure so that it formed a rough blocky equivilent to the final shape. Then the furniture was carved out and finished. The advantage was you could build "solid" wood in shapes that are not structurally possible with plain wood.

When I saw this, my first thought was you could build a hollow wood rudder by laminating strips of wood and composite for strength. You would not need the jigs and molds normally needed. Just build the rough shape around a hollow core and cut the outside to the final shape.

While this might not be as light as say a hollow core carbon, as long as you have access to a way of cutting out the final shape, the tools needed are simpler. Also since molds are not needed, it would be easier to build rudders with different foil profiles or even shapes.

I don't think this will revolutinize the world, but if you want to CNC a set of foils, its probably better and cheaper than starting with a block of aluminum.