So I actually tried doing this today mainly because the shirt no longer fits me. So for awhile I was thinking about what to do with it until now. This my version of this tutorial. Instead of two straps I just decided to use one. The main reason is because its easier for me to keep an eye on things as well as keeping it close to me. :)
I used some left over red cloth that was used to make my red and black curtains to make the single strap. As you can see, I also used a vinyl record to try to make the semi perfect edges. To put it all together I used yarn to sew the shirt, and regular thread to sew the straps onto the bag. :) And this my results :D