I'm sorry you took my attempt to make your life easier and instead of recreating the wheel offered other alternatives that did not involve the possible destruction of hardware.
I should have said,
Remove the refill
Use a transfer punch the size that will fit into and through the transmission
Holding the lower barrel and shifting the transfer punch to one side hit the transfer punch with a hammer until the tip loosens and comes away from the lower barrel
Turn the lower barrel over and insert the size transfer punch that will fit the tube and again holding the lower barrel in your hand hit the transer punch until the transmission is removed from the barrel
Use the same technique above to remove all hardware from the upper barrel.
Or
you could purchase an assembly vise from Penn State Industries but, oh, you dont want an advertisement.
Then, if the person that made the original pen used CA to assemble then you will need to soak in Acetone to break down the CA.
Was that better?