These are super easy to make, and I made one for everyone on my Christmas list who deals with any aches or pain.
You want to make sure to use the COOKING rice, NOT INSTANT rice!
Do not get wet, will mold.
Keep stored in a ziplock bag in the fridge. You can get it hot in the microwave, or place in the freezer to make it extra cold.
You can also do customized variations- such as adding dry cut lavender for people who suffer from migraines, or adding dry cut valerian for people who suffer from insomnia along with their pain, etc. You can even make full size back packs, adding "tubes" to keep it firm and in shape, and velcro & elastic to keep it in place when the person is using it.