Hi Lara, another potential method you could experiment with would be to have your base shape be just 2 extrusions, then draw in 2 profiles in the top view and trim those away and put in a blend surface between them. You may need to manually flatten out the top and bottom of the blend.

That looks something like this though:











But maybe that won't work for you if you have some specific criteria for the radius at each position though.

- Michael

Hi,
can´t express how I love this little fine peace of software...I purchased it years ago but it slept...like me...
...now I´m relatively happy with my model.
If there is something that can be modelled better please do not hesitate telling me..
cheers, thanks to all, Lara

Your object is not a solid!
Select bottom edges : Construct / Planar : Select All : Edit / Join = Solid
Save as OBJ and render inside the free Simlab Composer Lite :) (Maxi 1920 * 1080 - commercial use permited! )
http://www.simlab-soft.com/3d-products/simlab-composer-lite.aspx