How to smoothly cap this object ?

 From:  mkdm
7928.10 
Hi everyone,

first of all i wish to thank each of you for the help and the explanations!

1) To Michael :
Thanks a lot for teaching me a different approach.
It's not exactly what i was looking for but it's a good way for me to learn another technique in order to create organic shapes.

2) To Mauro (M-DYNAMICS) :
I followed your method and the result comes very close to what i wanted to achieve.
As wrote by you, filleting remains hard to do and i want to give me a chance to try Mike's method.
Thanks a lot.

3) To OSTexo :
Your result looks very nice and seems very simple to reproduce.
I will try your way and i'm curious to know if this method can lead me to get a more lightweight final object, in terms of number of control points.
But i'm wondering if with your method, the two side caps still preserve a good surface continuity with the chair's body.
Could you please tell me more precisely how did you generate the curves used to create the caps ?

Anyway, thanks again to each of you !

Ciao,

Marco.