This is a project I have already worked on some time ago, but added a few more samples this week. The idea was to turn a pile of worn-out T-shirts, which I did not want to throw away because of the attached memories, into something usefull. If you cut up T-shirts into long strips of about 2 cm in width, they make very good knitting yarn. So that's what I did with the T-shirts. For best results try to find ring-spun T-shirts, which are luckily mainly sold in North America, where I have travelled to frequently in the past.
If you want to save the memories attached to a perticular T-shirt, you can add a little embroidered label to the pot holder to mark its origin.