No problem PaQ!

Actually I think I've just come up with a more efficient way - again do the tapered extrusion about half way up, then select these 2 edges:




Then run Edit > Extend. The prompt will say "Select boundary objects or push Done for mutual extend". You want to do the mutual extend option, so right-click in the viewport or push Done without selecting anythiing else to activate that mode. That will generate 2 lines like this:




Repeat that on the other side so you have 4 angled lines. You can now delete the halfway extruded object, select the 4 angled lines and run Construct > Loft. Under Loft options, set "Loft Style = Straight", and also set a check mark on "Closed". That should generate all the top surfaces with one loft right there. If you want to seal off the bottom to make a solid, select the object and run Construct > Planar to cap off the bottom (for capping, it's a shortcut to select the object that has a planar opening in it and then run Planar - that will also do joining built in. If you build the bottom planar face from a curve you'll have to do an extra step to join it).

- Michael