You can use an unwanted sock (tube socks work great) or sew a bag for your rice.
If you sew your own, you can make it whatever dimensions you wish; just be sure to use 100% cotton fabric and thread so it will be microwavable.
To add scent, you can add the contents of an herbal tea bag or a few drops of essential oil to the rice before filling the sock.
Amen. You might want to consider sewing some handles onto it so you can tie it onto a part of your body.
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