I had a couple flannel sheets that I had sewed to be a comforter cover so I took them apart. The process was pretty simple.
I basically laid the bodyboard on the sheet and put pins around it to mark where to cut it. Then I sewed it on the sewing machine around 3 sides. It was too large so I sewed it in more and cut off the extra fabric. Then I turned down the top one time and sewed it to be a casing. Jerry had a shoestring that he wasn't using so we pulled it through the casing and the bodyboard bag was finished!
A few pictures are below:
Folded sheet in half
Here is the bodyboard on the sheet and I pinned around it to make the seam line.
Tried to show the green shoestring that we pullled through the casing.
Jerry and the new Bodyboard Bag