Cut several old towels into strips about 1 1/2 inches wide. Cut the long way on your towels so that the strips will be as long as possible.
Position three strips together, one on top of the other in a stacked arrangement. Use a needle and thread to stitch the top ends of the strips together.
Separate the three strands slightly and safety pin the top of the strands (where the stitches are) to a work surface in front of you such as a pillow on your lap.
Braid the three strands together as you would braid hair. When you get to the end of each strip, cut a vertical slit in the bottom of the strip approximately 1/2 inch from the end. Mentally label these strips A, B and C.
Cut a vertical strip in the top end of each of three new strips; mentally label these strips 1, 2 and 3. Pull the uncut end of strip 1 through the slit in strip A, then through the slit on the other end of strip 1. This attaches strip 1 to strip A; repeat this process with strips B and 2 and then C and 3.
Continue braiding the strips and adding new ones when you run out of fabric. When you have used all the strips, sew the bottom ends together as you did with the top.
Take one end of the braid and begin to spiral coil it around itself. Keep the braid flat on a table in front of you as you do so; after you have coiled a few rounds, hand-sew the sides of the braids together to maintain this shape.
Continue to increase the size of your coiled rug, wrapping the braid around itself in a circular shape. Keep the braids flat as you go and stop every few inches to stitch it together. When you finish, turn the rug over and use it in your bathroom.