As always, I decided to modify it slightly, to use dowels for handles instead of cord with grommet holes. I found this image on the Internet, and again, modified it slightly to allow a larger opening for the hand.
I chose a thick canvas fabric, and only needed 1/2 metre in total. I selected a 1" dowel at my home improvement store, 2 lengths of 20". I cut the fabric as follows, turned and sewed the raw edges on the long side and the hand opening. I folded the strap sides over the dowels and sewed them.