Open & Close Mesh-Manipulator
Mesh-Manipulator has an EditorWindow, to bring it up, select the MenuItem located at 'Window/Skele/Mesh Manipulator' or use the hotkey 'Ctrl+Alt+M'
The EditorWindow looks like this:
To get started, just click the "Start Edit" button to activate it.
Be noted that, the "Start Edit" button will be disabled if current selection doesn't contain a MeshFilter/SkinnedMeshRenderer;
Also when the editor is activated, you cannot change the selection of GameObject;
To stop the editor, click the "End Edit" button in the image below.
* What's the difference of MeshFilter & SkinnedMeshRenderer?
MeshFilter is for non-skinned mesh, i.e.: it's just a piece of mesh, it will not deform with bone, there's no bone related to this mesh;
SkinnedMeshRenderer is for skinned mesh, it contains array of bones and corresponding bone-weight info used to deform the mesh with bones.
* Can I use Mesh-Manipulator as Modeller?
No, Mesh-Manipulator is designed to morph existing meshes and make vertex animation.
It doesn't add/del mesh primitive ( vertex / edge / face );