Its pretty easy to do.
All you need is a ball made from mild steel similar to the original in size. This could be made on a lathe or roughly by just grinding a piece of rod to the approximate shape - it's not critical.
Drill a hole through it so that the cable slips through easily.
Now get your length right - measure twice cut once
You only have to cut one end of the cable.
Remove the cable from the car and insert the wire into the ball.
Silver solder the ball in place making sure that the solder wicks right the way through the ball.
Clean up and install.
Ken