Just tin a solid core wire and try to bend it. The difference is that when solder hardens its not malleable. Its not that solder is "harder" than solid core wire, its simply not maleable so you can't bend it (well without breaking it).
Actually the process is easy, I've done it to make UE cables and ETY4 (p/b/s) cables since I havent found those pins commercially available yet. I'm not saying to use the wire for the entire cable, just to make a 3/8" wire as the "posts/pins" for the wire. Actually I also did this when I was making a cheapo Sennheiser hd650 cable before cardas lowered the price to $16/pair (I know still exp but better quality). It really isnt that difficult, and as I mentioned, you don't need to find wire that's exactly the size of the connectors, find one that's slightly smaller and build your way from there. But before resulting to wires, I tried using pins from old serial cables, Jumper pins from when I built my gamma 1 and anything that looked remotely like it would work. At one point I even tried taking stranded wire, getting something "close to what I needed" then tinning it. And if I really need to make a custom wire that doesnt meet the standard AWG, then I would go down that route. Take good quality stranded wire and keep twisting certain number of wires wires until you get the right size, tin them and use that. When you tin stranded wires, you still get an "unbendable" pin for your westones.
Or assuming you have the old westone cable, just reuse the pins.