The fabric is nearly sheer, stretchy synthetic. I paid about $4 USD for the shirt several years ago and wasn't worried about ruining it by practicing. I used embroidery floss for the knots and a hoop to keep a grasp on the fabric. I think next time a backing would be useful, along with a different stitch or a patch. It was difficult to make the knots at first, and always difficult to close the holes without bunching the fabric.
