If it was me, first I would take a bodywork class at the community college. Then, I would anneal the ends with a torch. Next, I would take a ball peen hammer and a shot bag and just flare out the ends real gentle-like until I got the size and flare I wanted. Then you could work the thicker and thinner areas differently to keep the flare concentric.
Note: this all pre-supposes abilities and coordination that I myself do not possess. I'm hopeful of being bitten by a radioactive spider or falling in a vat of toxic waste though.
"The first rule of overkill: You can never have too much overkill." "Overkill is underrated."
