Well that was misleading. Thought you made a massive write-up on how to write it up. Should probably put a ? at the end of your topic title to make it less misinterpretative. Could you please update your avatar as well please. Thanks man.
In answer to your question though, there have been heaps of people who have made SNAPs here in Australia with aussie materials. You just basically have to re-adjust the materials to Aussie dimensions. The concept is the same. If you're wondering barrel material. We use 16mm UPVC for stock darts.
The bushing. Sorry. I don't know what that is :(. I think depends on the size of how big you want your plunger tube for your SNAP. You can get 16mm Conduit couplers as well if that helps.