You could fabricate any of the two on an aluminum alloy pole yourself by buying the end fittings and mounting them, but all three???
OTOH, two of those fittings, the harpoon and gaff, would be very dangerous to have on the back end of a pole being used for something else!
I, for one, wouldn't want to be behind someone who using a pole for something else with a gaff or harpoon on the end near me.
Maybe the pole types available come with one end fitting only for a good reason?
Next project: Multi-purpose pole with boat hook, gaff, harpoon, .410 shotgun (for Halibut), clam gun, and walking stick.
Will make you invulnerable to muggers. No concealed carry permit required!!! :lol:
YMMV!
Joe. :teeth :thup