You can do it without an extension. I can describe the method, with pictures, but not an animation like Box.
Start by drawing a cross section. Use the rectangle tool and the Arc tools to get this, after deleting the extra cross lines at the ends of the arcs:
Push pull it to HALF the maximum width (7/8").
Make it a component, and open it for editing in Xray view (View/Face Style/X-ray)
Make rectangles across the cross section at the ends of the arcs
Draw the taper, so you know how wide the bent piece will be at each junction.
Now use the scale tool in turn on the top face, the bottom of the arc, and top of the arc.
Select the top face, and Scale the width of the top to 1/4".
Window select the rectangle at the bottom of the arc, and Scale the width to match the taper you’ve drawn below it (draw a line across at the join, to get an endpoint .
Then scale the top of the arc using the eyeball, or calculate what the width ought to be round the curve.
Clean up by hiding the rectangles.
Mirror the half you have made - either use the TIG Mirror plugin, or Move/Copy then Scale -1, and move the two halves together.
(Green scale -1)
Delete the faces where the two halves meet, while they are still apart.
Move the copy to join the original.
Delete the straight lines where the halves join, and hide the arcs.
Have just realised you could do it on a full rather than a half section, using the Scale about centre option instead of Scale about opposite point. Would make a slightly cleaner component in fewer steps.
Anyway, here’s the model resulting from the above steps, saved back to v2014 so you can open it in v2015:
Steam bent taper.skp (31.6 KB)