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.
The blowout was a long the center seam, then into the seat fabric.
I used polyester sewing thread and backed the mended area with a piece of a knit shirt. The shorts are somewhat stretchy. I tired of hand sewing and used a sewing machine for the horizontal stitches. On first wear, Spouse popped some of those stitches. Spouse wears the shorts to work in a school IT office and to golf. Most of the repair is holding firm.
It was a learning experience. Probably the machine stitches would have lasted longer if a zigzag or other stretch stitch was used.
