I have also been working on a bunch of rice heating pads. They are made out of towels. You fold one in half(right sides together) sew down the sides and turn it right side out. Then sew 3 lines equal distance apart. Fill those tubes that you made with rice. Then sew the top. I also like to make a cover so you can wash it if it gets dirty. Again you fold one in half(right sides together) sew down the sides and turn it right side out. I also use bias tape to make little ties as you can see in this pic.

I just love how these come out!