[header] How to make a heating pad [title] Fill an old sock with uncooked rice. [step] The most simple method for a reusable rice-filled heating pad. It just requires and old sock, some rice, a microwave and something to tie or sew the sock shut. 
First of all get hold a a good sized clean cotton sock that you won't miss, and then pour in the rice. [substeps] There is no fixed amount of rice to use, but it is recommended that the sock be at least half or three quarters full.