How to create a mesh that you can stretch in Unity3D?

Thanks in advance! I’ve been searching for an answer past 2 days!

I want to export my really easy blender model (a hexagon consisting of just 12 vertices) to Unity3d.

In Unity3d I want to be able to change the transform of parts of the object.
However, it only lets me move the entire mesh! I want to stretch the mesh!

How do I make give a vertexgroup an own transform?
PS: Examples of what I mean by stretching only a part of a mesh can be seen in the image.
Note in the hierarchy that they use bones.
I’m new to this forum so if you have tips, you’re welcome.

You can only scale the entire mesh in Unity. If you want more control over the vertices, you either have to modify it in Blender, or make/buy modelling scripts for Unity: