I have made two different varieties - one for the sole of your slipper, to wear while sitting (it is a little uncomfortable to walk on the inserts and raw rice) and the other to lay on the top of your toes (which you can wear while walking around).
Additionally - similar inserts could be made to insert into your mittens. Just had another idea - the inserts could be slipped inside your boots too!
Step 1: Materials Needed
Raw rice or whole buckwheat seeds or buckwheat groats (do not us buckwheat hulls)
Step 2: Creating Your Inserts
Similarly, trace the top of your foot on a piece of paper. Cut two tops from the pattern - again flipping the pattern over so you are creating a right and left top.
Step 3: Cutting and Sewing Inserts
Pin and straight stitch 1/4 " around, leaving a 1" opening. It would be a good idea to stitch again just to be sure the seams are secure and rice grains aren't able to escape in the future.
Turn all inserts right side out.
Step 4: Filling Your Inserts
Stitch opening closed - again, consider stitching twice.
Step 5: Ahhhhh -- Enjoying Your Inserts
Now insert your inserts into the microwave. As each microwave is different, and the amount of rice or buckwheat used is different, heat on high for 1 minute and continue heat testing until just right for you. Use caution!
The rice or buckwheat should retain the heat for up to 40 minutes.
Now insert your inserts into your slippers - ahhhhhhh!