I have a few old feather/down pillows that don't stay fluffy anymore. I run them through the dryer with a trio of tennis balls, but after one night of sleeping on them they deflate. So I have recycled them into throw pillows for the couch.
First I shift all the down to one side and pin it in place:
Then I sew along the pins and eventually serge the edge too, so the down doesn't escape:
Then I make a lovely pillow cover for my "new" down form:
In this case, some lovely Amy Butler fabric. The pillow is a little smaller than I planned... I had an accident with the serger, and it caught a bit too much fabric.