I wanted to start animating with something less complicated, so I choose a blacksmith, without people, just hammers forging a metal bar into a sword. The only way I could think how to animate the transformation of the metal bar into a sword is to model a sword and a metal bar, the sword put into the metal bar and then animate scaling the metal bar down after each hit of the hammer. Is there a way to make the metal bar transform or should I do my best using scaling?
You can use shape keys.
Model your sword first. Create a base shape key. Then add a new shape key and start deforming it to to the shape of the bar, creating new shape keys along the way. Animate then the shape keys values so that you are left with the base shape key at the end.
Then just let the swordsmith do her job!
The example Blend file is HERE