I think this would be a great project if you have the time right now. I know that once you have the pattern and process down you will be able to make these items in record time! Just set-up a production line and you will be "in business". My thought is that you will have more orders than you imagine. This is a 'hot idea'...
Thank you for your insight. I believe you are correct about the corn being to dense for the heating pad it do much good. I am going to try using my counter-top convection oven. I have a titanium pan with an oven safe glass cover that I think would be safe to heat the corn-filled heating pad.
I will stop by my local feed mill tomorrow to get some feed corn (very cheap). Sew up a bag with the quilted channels for the corn, then test it in the convection oven. I will post my results.