Just a rectangle and a circle...one curve rail...
this internal cooking of number of pts is not very important for the moment...
it was just for try to understand in deepth

<< the "# Points" mode is another style of rebuilding that samples a uniform number of points along the curve for the reconstructed curves. You can choose how many points are used.
<< This mode results in very smooth output, but small details in the profiles tend to be lost.

I understand that and funny to see a rectangle becomes a section of a wing's plane! :)