Matt, I'm not sure if that's what was meant by buying the jig. The way I understand it is that there will be a jig manufactured to make the water rail. The jig will then exist for Graham Bates to manufacture the water rail and sell the water rail to anyone he chooses. If we, as in however many of us want to chip in for it, choose to buy the jig, then Graham Bates will only manufacture water rails for us, therefore creating a 'point of sale' by making it exclusively available as a retail item from us, rather than him.
I may be wrong of course, but that's how I'm reading it. Please, Mangocrazy, correct me if I'm wrong!
Andrew.