Yeah, having done this in three countries now, there are several main issues.
1) if you build it, they will NOT come.
No matter how many say they will, when it comes down to making the effort to actually go somewhere, most just won't bother.
2) it must be held in private land. Otherwise event insurance will be insane.
On private land you can get people to sign their lives away in a 'not our fault' agreement.
So those are the main negatives
What does work is actually much easier than setting up an event from scratch.
Find an existing event and latch on
The most successful events held in the UK have been at the bushmoot in Wales.
Bushcrafters take to slinging like a dead rabbit to a firepit.
So places you could successfully run a slinging event.
In the states, my first choice would be at a renfaire, we don't have them in the UK - but from what I've seen they would be perfect for a slinging workshop and competition setup.
Bushcrafting events.
These are perfect and if proposed correctly you could even get paid to run sling making and using workshops.
Survivalist events, pretty much just the us, but definitely worth looking into.
You'd probably need to pack some razor glandes
Or just take Joe and some big rocks
But setting something up from scratch, is expensive, thankless and incredibly time consuming.
The thing about pep Ribas Ribas, is that he's a born politician and somehow manages to get local government sponsorship. Also lives somewhere where slinging is culturally important.
The rest of us are on our own.
So find an existing local event, preferable one that lasts several days and piggy back if it.
Longer events are better as you'll need to have sling making workshops and sling usage workshops, leading to a final competition.
If you can do this several years running, you will build up a core if slingers who can help with the workshops and gradually expand the scope of the slinging events.
Dave's been running sling classes at bushmoot for a few years now.
I took a target down one year and taught them to make sockballs, which led to running battles throughout the camp.
I think I even made back my petrol money in sling making materials.
One of these days,Ill go back.
Although given the current cost of fuel, I doubt I'll ever break even again.
There used to be a big bushcraft event just down the road, but just never managed to get any response from the organisers and it's now moved to Milton Keynes.
Just bear in mind that you will most likely be limited to tennis balls for target slinging and sock balls for interpersonal combat.
Anything else will require insurance, and if you can get it for using Rock's with slings - the cost will be eye watering.
Tennis balls, never seem to need anything.
Just be grateful that people have no idea how hard sling thrown tennis balls can hit !
I dont - personally - consider tennis balls safe for interpersonal battles.
Fortunately people who've never seen slings in action, don't realise and generally have no objections to using tennis balls.
I've used sockballs in mass battles between: scouts, young farmers and bushcrafters - they are proven injury proof ammo
They also fly further and straighter than tennis balls.
As far as events in Oz go
I have not a clue.
But I would imagine there are bushcrafting events, it seems a popular worldwide movement at the moment.
But to sum up, my main advice is to not try and do everything yourself.
In 2007, we built, probably the best sling range ever made on George's land in Wyoming.
5 people turned up.
Fortunately one of them was Larry bray', made it worth it for me
I held an event on private land in the uk in 2008, and about 16 people showed, which was a good number.
With the increase in YouTube videos and the larger group of people aware of slinging, theoretically, you should get larger numbers.
But I very much doubt it.
You will get more people at bushcraft events who have heard of slinging, but also more people who think they know what they are talking about, and really don't lol
So that'll make life fun