the fusable stablizer is just an (assistant) to help control the stretch of the t-shirts, if you are going to use cotton in the center of the quilt, using it like a foundation for your t-shirt blocks would work just like the interfacing...it is your interfacing...just without the fusable added. you could (baste) your t-shirt blocks to your sheet, or you could (window) fusable. so it is just around the edges to hold it until stitching. some sort of interfacing is needed. it does not have to be a fusable one....you could do a type of quilt as you go and (quilt) each t=shirt block to the sheet then join the fleece/flannel back pillow=case style ...and just tack in places to hold everything to gether