Thanks again for your helpfull answers...

Malc615 --> you have exactly what I was looking for. So, the only thing I had to do with my first attempt was to divide the main shape in 2, and use network tool.
So cool ! I can go on with the other parts

Michael :
"You can also use sweep for situations like this with 2 longer guide curves"
Yep,I tried it, it also works but I have less control on the volume...but it's usefull.

"For network it can be easiest to get a smooth object by doing the full object all at once instead of half."
That's what I was trying to do at the beginning, but it didn't work. Now, with the Malc615's advises it's OK.


(sorry if my english is not so good)

Post soon, when done !