Cut two pieces of flannel in rectangular shape that you like.
 Place wrong sides together and sew around all edges using a 5/8" seam allowance.
 Clip to make a fray around all of the edges.
 Throw in the wash to make your edges fray up, these are some that I made couple years back they were well used and they work great.  The frayed edge is actually very absorbant.
 
