create a shell

 From:  edlhn8

I'm trying to make a kind of shell by sweeping two pentagons (but I suppose the number of sides doesn't mind) along a curve. But I don't get the desired effects. I don't know if I'm doing wrong or if I could get the same shape witH an alternate method. I think that with the model it's quite easy to understand what I'm trying to get but I ca'nt get. (I'm still a noob with NURBS)