I have made a few of these they all look great, to stand the rigors of use and laundering I also "tacked" a few stitches at the base of each fold, I also top stitched around about 1/2 inch from the last fold, this not only looks good but also holds everything firmly in place.
I also cut my strips 6" x 3 1/2" and then folded over 1/2 inch to make them 6 x 3 it gives a much neater finish,