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