From what I understand, there is a difference between the boiler being certified, and the operator being certified. The boiler has to be certified, but for small boilers in at least some cases the operator doesn't.
Using the example of the people that build and run model steam locomotives, model steam traction engines, model steam stationary engines etc; they must have current certification for their boiler, if they want to publicly run it. Since many of them belong to a club, and the club is linked to their Australian peak body which maintains their boiler code, they can get the club certifier to do the pressure testing and inspection they require. But the operator doesn't need a ticket.
They know that they have a privileged position in that they have managed to keep industrial requirements at bay by actively lobbying the Worksafe-type authorities and maintaining their own code. Its an odd thing but many of these steam loco clubs are called "such-and-such society of model and experimental engineers" because historically it wasn't just about building model locomotives but about blokes who made a variety of stuff on their lathe in their shed. Its possible that some of those societies might entertain room for home workshop machinists who want to make solar steam sets. But its all about social values at some level. If you come across as sharing an interest in using machine tools at home to engineer something nifty, all good (especially as many of them want to attract more members); but if you go in among this bunch of slightly older and conservative no-nonsense practical blokes, and start on about greenhouse gas and nutty perpetual energy machines, it isn't going to happen. Not that I'm suggesting anyone would, but you see what I mean.
I'm not sure that joining such a club is necessary at all, but it might solve some problems on the boiler side. But whether or not, I still reckon it would be a fascinating thing if someone figures out the way on this.
