yeah i see what you mean, well I tried your technic and it's okey I've got the volume but can't really fillet edges the way I would like. It's a pitty, there's apparently no other turn around. That's kind of sad :(

However, why wouldn't it work to apply a fillet function on the edges I've selected ? (as seen on the screenshoot) Ho yes, I first filleted the problematic edge so that it's more "smooth". By now it doesn't seem to work but is there something I'm doing wrong ?

And yeah, I'm afraid to switch to those kind of heavy CAD package... those software are more likely for engineers and well, I'm more "design oriented" artist though... I don't know if I could learn as easily and as fast as I learnt MOI. Moreover, prizing isn't obviously the same huhu :)

But good friend of mine who's studying architecture in University in Switzerland spoke to me about Rhino or something. He told me it was great for modellisation. In your opinion, is it more likely to work with this software for that kind of fillet task ?