I have at my disposal 44mm and 55mm (1.73" and 2.16") internal diameter PVC piping at my disposal in an approximate 28" length. Unsure if I should cut them up into 2x14" pieces or what. Similar to this guys work.
I'm still deciding and gathering intel on my "problem" anyhow, to be utterly sure I know the actual address of it. (I'm still attempting to handle this problem via "sane" means)
I have decided though, that if I can't get it solved amicably, that I don't care how much power I need and the expense, to an extent. I also don't care if it's partially audible to humans either - I've read several comments from people, seeming to indicate that some of the stuff in the human hearing range (but high) was actually quite effective with dogs.
Honestly, at this point, I don't care if it shatters buildings, knocks down walls and summons demons, but sincerely doubt that's possible with something powered by a 12v DC motorbike battery and in a small backpack.
(This thing I guess, will look something like a Ghostbusters proton pack)
I also may consider a pringles tin if it will assist. What's important is that this thing gives a sharp, nasty wham to a creature easily 55' away (at closest)