old t-shirts (22 were used in this project)
heavy thread (eg. quilting thread)
backing fabric (about 1.5 yd, depending on your finished rug size)
2. If you pull gently lengthwise on each strip, the fabric edges tend to curl in on itself from the sides. I put the ends of three long strips together, inner side of the fabric facing up (the edges thereby curl away from you and you don't see the raw edges), and pinned them to a heavy window curtain. You use the natural curl to make the strips more rope-like, which makes them easy to braid neatly. You may be able to think of something else to pin the braid to, but i found it comfortable to work standing, the braid pinned at about eye level, and then i could braid quickly for 3 feet or so, before unpinning and raising the braid up and re-pinning at about eye level again to continue braiding. You want the braid to be fairly tight.
3. To coil the rug, you want one super long length of braid. When you come to the end of one t-shirt strip while you are braiding, you add another strip to it. Here is a really handy method, which avoids the hard bump a knot would make:
4. Braid all the material you have into one very big pile. You can finish the ends off by taking several stitches, in place, through all three layers of material and making a knot. This tacks the three ends together without making a bulky knob.
5. Starting with one end of the long braid, begin coiling. As you were braiding, you always try to keep the side of the braid facing you nice and neat. So when you are coiling and stitching now, keep the "untidy" side of your braid facing "up". I opted to make an oblong-shaped rug by keeping the first about 1 foot of the braid straight, and coiling the rest of the braid around it.