I started a rug a long time ago from t-shirt yarn. (project 19) It was never finished. I unravelled, all the circles and started to make a simple rectangle. It would be simple, except the yarn was of different thicknesses and weights. I crocheted with two strands of yarn to make a thicker pad. It took a fair amount of undoing and redoing to get the rectangle to be even. I used some of the scraps from my t-shirt quilt to make more yarn for this project.
I am using the finished pad as a Critical Alignment Therapy prop for the lower back. There is a felt pad that is sold for this purpose, but a firm blanket or towel can be used instead, or a crocheted pad. Size and placement of the roll change the effects. It is safe to do, but it can be a very tender area to investigate depending on your history and current state of your lower back. You are after all just lying on a rolled up blanket, but the sensations that can arise can be strong. The purpose of this exercise is to mobilize the lower back vertebrae. Lying with the lower back supported by the roll is a passive backbend, to be followed by exercises to coordinate the movement of the lower back and strengthen the spinal muscles while releasing strained muscles. So if you try this, go slowly, stay for a few minutes and then lift your back off the roll and remove the roll. I would recommend going to a Critical Alignment class, or find a teacher (me, for instance) to learn what this exercise is about and to learn some complementary exercises. It is a very important simple exercise to help the lower back move towards neutral alignment. You’ll feel much better afterwards and not just because it’s over.