You're globaly right Brian.

The green, red and orange curves began life as "smooth" iso-curves of the cushion.

Yes, they are concentric because of the revolve rail used to construct the cushion.

The red curve is an iso as is the green an another iso.
The red one has a z distortion

Yes, the Orange is an iso with a XY distortion applied.

But the blue is a clone of the orange with a scale (the cause of the similarity). I made the blue because when I did the lofting I didn't have sufaces which could be joined as solid.
Blue is used to cut the flat top before doing a blending.
The blending gave me a surface to join and have a solid.

I always do solids because I always do models for 3dprinting.
But for a illustration it's not so important... or useless.

I don't remember when I add rebuild or reconstructcurve, but I do it often to smooth or delete the hard angles.


Have a fun Moment Of Inspiration !

Francois