This seems a very easy puzzle, the same kind of meshes (only differ in different heights of points); and then closing the space in between.
It drives me mad. I tried many things and still continue doing it wrong.
How can I close the space in between?
problem close mesh boundries 00.gh (25.4 KB)Like this?
problem close mesh boundries 00_V2.gh (13.0 KB)
Those meshes aren’t actually the same:
If they were, you could get the naked perimeter edges (as closed polylines), and make a mesh from these two point lists. An alternative approach (assuming your meshes are always planar), is to simply offset the mesh (with the solid flag on) using the known height as the offset distance.
Thank you 
I am trying to get a closed mesh from it, or a closed brep with ‘Mesh to Polysurface.’
Do you know how to make it closed?
I was thinking of simplifying the mesh, to get it closed and get a closed brep of it, but it did not work when I tried it.
The meshes will not always be planar.
I know tried to ways of doing, but what dit you mean with the naked perimeter edges? So, python, then getting the naked edges and then what I can do with it? I understand points can be connected, but how did you mean it?
problem close mesh boundries 01.gh (28.9 KB)
This should be a workaround, if you’re not reliant on the exact topology of the second mesh.
problem close mesh boundries 02.gh (23.2 KB)
If you have two topologically identical polylines (i.e. the naked mesh perimeters), it’s trivial to bridge these with a mesh. Here’s an unscripted implementation:
190418_ConnectMeshesPerimeters_00.gh (15.6 KB)
But again, your meshes aren’t identical.
