made about 30 of those things and have found that Pellon Shapefuse (it's a woven net that is stetchable in one direction only--be aware of which way the stretch is going--best if opposite of the way the t-shirt stretches most) is my go-to. A LQS sells it in 54" width which means much less waste. My next fav is Pellon 911F--it's very fine and flexible,but doesn't seem to fuse quilt as easy (really needs heat and steam) and I can only find in 24" width. I fine that the all poly shirts (like soccer shirts) and those that have the holes in them are needing less heat to fuse.