I am wondering if someone can recommend an extension or tool which will help me create a model which looks quite similar to this
Try using SUbD. You can download this extension by clicking on either of the boldfaced links below:
SUbD - Extension Warehouse
SUbD - SketchUcation
Here is a video showing how to use it.How to use SubD in Sketchup (Subdivide Quads in SketchUp)
If you're looking for a free alternative, you should check Curviloft plugin. Skinning feature of that plugin suits for this.
In the video below i drew lines with Bezier Spline plugin and gave thickness at the end with Joint Push Pull Interactive plugin.
Or you can use Bezier Surface extension.