How can I connect the edges of two geometries to create a thickened effect?

I have a geometry and I want to create a thickened version of it. To achieve this, I cloned the buffer geometry and moved its normals inwards. Now all that remains is connecting the edges of the two geometries to form a solid, thick structure.

Here is a screenshot of my current progress:

Is there a more effective approach, or any recommendations on how to better connect the edges of these two geometries?