Hi Finema,

>>i don"t understand your technique...

I've used sweep...



for rounded result you can try to use two curves start/end and rails connected between ends of these curves. I used only one curve and point ended rails.



The cyan curve is tilted in right viewport - half angle between perpendicular and transversal part of vase.



...then I jointed surfaces. Resulted surface was copied and scaled (0.99). I've created the solid via jointing lofted surface between outer and inner rim of surfaces and outer and inner basic surface of vase.

Hope this helps.

Mik