I use batting in the center because of the cost for flannel... BUT.... when i sew the two squares together, i slip in a strip or two of 1.25" flannel pcs..... I have done one extra, but prefer 2 or 3 different colors, both from themselves and from top and bottom squares... this makes it look like there are lots of layers and after the 'ravel' wash and trimming, you have lots more personality to your edges without all the cost.... one of my faves was a navy poly silk jacket with the navy on both top and bottom but each set of squares had either daisy yellow, grass green or candy pink inserted in the seam.... the little touches of color really made the jacket... it was one of those simple 'graph paper' kind of pattern where every pc was made of squares... i think i took it from a crocheted, afghan version of a jacket and just counted squares.... it's been a long time...