Michael,

as usual, your tips are very useful. To get a pseuso render real quit like that is a great idea, thanks.

I suppose I can shrink (scale down) my second profile such that it doesn't fold on itself like it does now but this will also affect other aspect of the model that I'd prefer not modify if possible. I did this to create the red model kind of thing in the last image I posted. For this first attempt I used an open profile curve to generate the sweep, I was just fooling around and then decide it would be nice to use 2 of these objects and join them with a nice flowing shape to connect them. I realised I needed a symmetric profile curve such that it would be possible to use these profile as well for the connecting part.

Personnaly, I have 2 problems with this models, the first is obviously the self intercecting part and the second is that a real object like this wouldn't have empty space like it's clearly visible in your image (felix_self_intersection3.jpg). I guess my question would be, is how can we design such object without self intersecting part and with no voids? Any suggestion will be helpful, I have no doubt about that.

Thanks,
Felix