okay well basically with blendshapes, you are creating targets, which is simply ur model in different states i.e. before it melts, when it becomes gooey, when it is stretched apart - these are targets. In using blendshapes, Maya automatically calculates all the inbetween movements so u dont have to. The best example for all these as u can imagine is in facial animation. If u can understand how, with blendshapes, u can make ur character smile, all u need to do is apply the same principles to ur needs.

What ud have to do is take ur model as it is, duplicate it several times, and then adjust each model accordingly.

I hope this helps. Im a bit tired now so i may not be making this as clear as i could lol

I tell u what, I'll knock up a file for u giving an small example