Increase thickness only on specific parts of a 3D model I am trying to improve the model shown below. As it can be  seen, the cloak of the model contains some holes. I tried to apply the Solidify modifier, but in this case the thickness of the whole model is affected (i.e. the neck of the model becomes to wide). Is there any way to fill these holes?
Some modifiers have an option to affect only specific parts of a model defined by a Vertex Group.

The workflow is like this:

In Edit Mode select the vertices you want to affect, create a vertex group by pressing the Plus Sign on the right of Vertex groups.

Click then on Assign to make the selected vertices part of the newly created group.



To use the modifier on a specific vertex group, select it from the list available groups:



Vertices that are not part of that vertex group will not be affected by the modifier.

NOTE: If what you are missing are faces on the mesh, the solidify modifier will not fill those gaps. It will only make the surfaces of existing faces thicker.