It's not an exact science. I don't know if this will help but I put a bunch of information on making foam swords over here (https://www.instructables.com/id/DIY-Foam-Weaponry...) that might give you some ideas. Let me know how it goes!
Hmm, I'm not sure, it's been a while. Maybe here? I looked up "filament wound epoxy tubing" on google and found a few different options, so probably pick the one that works best for you.:D best of luck making your staff!! I'd love to see pics when you're done.
Oh, I forgot, I used two cores. I got the fiberglass from Home Depot.
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