I whipped these up last night. The front is in a toille fabric and the back is in a red & white gingham.
I sewed the four corners of the toille fabric (measured 4 inches with an additional 1/4 of an inch to fold under, i guess that is called "seam allowance"?) and used the double sided iron on adhesive stuff to adhere the gingham. It also makes the coasters pretty sturdy.
Everyone I know is gettin a set of these for Christmas!