I used a hollow metal broom-handle that we had lying around ...
... and cut it into two lengths, about 50cm (20 inches) long.
Then I threaded some rope through - this is what I had already (not sure I would have picked the bright green colour!)
Once I judged how long I wanted the rope I tied a reef knot and pulled it tight with some hot glue in it to make sure it held well.
This is how it looked:
I swiveled the rope until the knot was inside the metal tube.
Then it was ready for action! All I had to do was fold the duvet into quarters length-ways and hang it over the metal bar.
A couple of S-hooks from the dollar store and they were ready to hang in the closet freeing up some shelf space.