Hi osx59 - here is a bit more of a description of the alternate method, this is pretty rough but might give you an idea on a different approach.

To start with I drew several curves like this:



Then I used Construct / Loft to make a surface out of them:



Then extrude that surface to get your volume shape:



Get some 2D curves on the bottom to act as cutters:



Do boolean difference to cut those out of the shape:



Then this has a much fewer number of curves and corners that have to be built, this kind of thing is more easily filleted:



That kind of an approach has a lot fewer pieces involved, that can often times make filleting work better.

- Michael