Or sleeve and drill holes and punch in pins. No heat.
edit: second on that ball, it turns out.
I think a shrink fit is difficult to pull off - as in succeed with - as you need really good tolerances and a good sleeve material.
Crimping would probably do the trick but to get a hexagonal crimp you'd need the correct tool.
I think it would be perfectly possible to heat treat the longer version, cut and bend and then heat treat again to return to perfect spring condition. You'd need to know what process to use, that's all.