OK, I pretty much had to do it "old school", like the modeler in Pilou's video. Every time I tried to use some fancy tools like Blend.rb or RoundCorner, something either didn't work, crashed, or returned something unusable. So - it was basically "extrude" followed by "scale" and some minor fussing with the alignment of the resulting shapes, and lastly "soften edges". It's by no means precisely what I wanted, but it's pretty good. I guess I just have to remember, just because we've got all these fancy, fantastic scripts from the community it doesn't mean that the simple things should be forgotten.
Thanks everyone for the suggestions and I appreciate the help!