Cut the whole front off the tee shirt and fuse a lightweight interfacing to the back of each tee shirt. I place the right side of the tee shirt face down on a teflon pressing sheet and then fuse the interfacing on the back side. Do not iron the interfacing, press and hold, then move the iron to another place and press and hold again until the interfacing is completely fused. The teflon helps prevent any "meltable" things on the tee shirt from sticking to the ironing board cover. Then I cut the tee shirts in the size blocks I want them in, usually 12 1/2 inches squares. Then add sashing and a border. If the tee shirts are stabilized correctly, they don't stretch when the long arm quilter stitches them. I have made several this way and they have turned out great.