Sorry I misunderstood your original post. If someone wants to use the mould to make more boards I'm sure they are welcome to borrow it from whoever is storing it. I don't know how the cost would work out as its a slow production process. Although it only takes a couple of hour at a time for each stage, most of the time is waiting for the resin to cure ready to do the next stage. So I'm not sure how someone would charge it at a commercial rate. I guess there is about 16 - 20 hours of work total for each board with prep and finishing but not sure how this would work out at commercial rates. If someone can be found to do the work I guess it could be more cost effective to make say 5 boards but not sure who would do it or what they would want to charge per board - but if the demand is there .....
I agree that owners should either have a spare or at least have access to one if they get damaged as its quite easy to damage them beyond repair. Once the central internal stiffener is damaged they can't be repaired. Even quite minor damage is difficult to repair properly with them being a hollow floodable part as they are deigned to break before they do damage to the structural part of the boat they are in.
I still haven't worked out how the rudders are built as although they appear to be a similar hollow flooded design to the dagger board the smaller thickness makes them more difficult to mould and then bond the two parts together. I guess someone will have to cut one open to find out at some point. That's how I managed to reverse engineer the dagger board to make sure it was the same as the original. Making an external shaped mould is the easy bit, and in principle the construction is the same as for the dagger board (full details of which are now downloadable from this web site) the difficult bit is working out how to make the edges bond properly in such a shallow part without introducing distortion - no one wants a bent rudder. It turned out to not be a problem for the thicker section dagger board. I now have two new ones.
Mike - Tarka 26M