Again we'll ahve to play match the blurb to the picture...here it goes...M
First I cut a long recatngle of material ( I chose flannel so it would feel soft against the skin)

Then I hemmed each end and turned it into itself, so that when it was finished I could turn it right side out again and have an envelope.


Then I sewed down the two sides

And voila I turned it rigth side out and popped the heat bag into it.


You can use this same idea to make really quick and easy thorw cushion covers.