When I have made tshirt quilts, I use my 12 1/2" square ruler to cut the graphic design from the shirt. Very convenient! I back each knit square with cotton calico, muslin, old sheets, or something similar. I like to use sashing between the blocks, too. It's pretty heavy at this point, so carefully consider what kind of batting and backing you want. Tshirts and the inks used on them can be hard on your needles. I think I went through 17 needles on the last one I made - It was double-sided tshirts and had a cotton batting.