yeah, it's kind of deceptive :( I'm trying everything and nothing can't really get done the way I'd like it to be... I can't imagine I've got something impossible after having seen some object design or car industry modellisation with MOI on the internet. It's crazy !

I think you made it clear about filleting being sensitive to curves angle (thanks for the little animation ;) )
That's why I've tried another way of generating the surface, I mean another structure. (as seen in the screenshoot)
However, in screenshoot no.5 , I zoomed on the little area (the same you zoomed in) and well, there is something weird, I don't know why ? (it's a sweep opération between two edges and two rails)

Is there anyway of filleting the yellow edges ? It's killin'me :)





















EDIT:

sorry, i haven't seen the last post you made :D I'll check this technic ! Thanks a lot for taking some of your time to help me out ;) By the way, How do you know my name ?! :P