There is a bit or work in it but it was made a lot easier by having a mate with a CNC machine to cut the foam blank. It weighs around 12kg because, with it being that long (nearly 9ft) and thin, you need quite a lot of carbon to make it strong enough. The mast is over 40ft tall so there is a lot of horsepower in the sail plan.
We also made a plug for the rudder. (Pic Below.) Mark cut it and I finished it. But I never made the mould. I decided I wanted a slightly longer rudder for the main hull. So Mark was good enough to cut the foam blank of the rudder in the pic above. Once launched I'll probably go ahead and make the mould and use that to make some float rudders. I'd like the redundancy of the 3 rudders when coastal sailing.