hey having a back ground in fibre glass its definately the way to do and if you make an internal mould put a few dril holes in it and plug them with plastercine then lay up over the mould, then when you are finished use an air blower in the holes to pop it off the mould. if you make the internal mould the right size the outer case you have just layed up is now your new mould. time consuming i know but try doing it for a full yacht its a bitch!!!