I have made about 5 quilts using the Too Cool T-Shirt Quilt method, also. I also did not use interfacing. I really don't understand the issue that people have with making them. I bought the templates for the Too cool T-shirts.With these it is just a matter of determining the layout - since all pieces are in increments of 4 inches (plus seam allowance) - 4 x 4, 4 x 8, 4 x 12, 4 x 16, 8 x 8, etc. This way you get to customize the size of pieces to the logos on the quilts.
I enjoy making them.