Aras, you said, “I think that the second method (video 2) cannot be applied to geometries with different shapes“.  That is not true. The Fluent Meshing approach is the easiest method to apply to different shapes. There are minimal operations to the original wing STL data. Each wing would be subtracted from the same air block in SpaceClaim on the Facet tab using the subtract tool. This is the method that keeps the resulting mesh closest to the original STL and takes the least amount of time.

The SpaceClaim Autoskin tool requires smoothing of the trailing edge, so that results in a significant deviation from the original STL, however a mesh can be created in a similar amount of time to the Fluent Meshing approach.

You say you prefer the SpaceClaim Skin Tool. You keep asking if geometry can exactly match the STL. Pay attention to the video at time 7:50 where I show that this surface is not exact. This video was made to show you some tools you can use, but it is by no means the complete solution to creating geometry that you can mesh.  Three difficult areas are unexplored.

The first difficulty is matching surfaces at the boundary between one 10 mm block and the adjactent 10 mm block. Planes slice up the STL facets so the facets match exactly at the plane. One skin surface is created that approximately follows the facet edge on one side and another skin surface is created that approximatly follows the same facet edge on the other side, but unless you picked the exact same points for each surface, the spline curve will not be exact. I think that by the time you mesh the solid blocks of air, a Mesh Merge operation will allow nodes on each side that are very close to be merged into a single node, so this difficulty can be overcome fairly easily.

The second difficulty is slicing up the leading edge of the wing which I called the front in the video. This may require the solid body to be cylindrical or elliptical instead of a rectangluar block so it can approximately follow the normal vector from the STL. Perhaps this cylindrical or elliptical block of air can be merged with larger blocks of air to make the inlet boundary.

The third difficulty is slicing the block of air behind the trailing edge. This will require extending the trailing edge to create a cutting surface for the air.  Maybe you can simply pull the rear edge of the surface. I don’t know.

In summary, slicing up the air into blocks and using the Skin tool is going to be a very time consuming exercise and will be a different challenge for each new wing shape.  Contrast that to the Fluent Meshing approach that takes very little time and is the same few steps for each new wing shape.

Good luck in your meshing and simulation project.