Thx a lot for the answer Michael.

So it seems very hard to model this kind of shapes with nurbs if you not have a parametric way to tweak the curves after the boolean trim, to get this streamlined side edge as you want.

I tried the method you showed with sweep, but couldn't get the side edge sorted as it is in the model by boolean trimming, even after many undos and redos, curves --> sweep --> bool trim -->undo twice, and again.

I can have that shape in minutes with subd, or classical poly method, but it would be a total fake for dimensions, surfaces bending etc ...
By using polys and lattices associated witrh curves it's possible to work with such kind of streamlines, similary as with nurbs.

I'm a bit disapointed, but thats learning, and also, the shape in the last 3dm/screenshot is quite near the real one or at least to what I wanted, just these weird edges are frustrating me a bit more.

Same for getting rid of these sharp edges after mirroring a half model. I didn't expected that.

And I still wonder how they've done this model, I mean the designers. I cant believe it's made with subd, you cant get any prototype out a printer from subd, no piece or hole would match another really, among other distorted curves and surfaces( and bevels and uneven thickness ...) problems I guess, and the fact they would certainly have to redraw it entirely in the end for the same reasons.

Anyway it would have be pretentious to think it's that easy to draw, ignoring the tons of work and knowledge behind such a model, I'm not a designer.