Hello! And thank you for this great description. Am pretty sure I get the 'picture'. I was wondering if it made much difference if the two 'plates' were positioned separately from each other, as in on opposite sides of the feet. Su current would pass between the two.
But it appears it does not make that kind of difference. I will purchase the graters that you describe as I was staring at them today, but held off. Thinking I could be smarter somehow... but methinks your design is spot on. So I will follow your lead.
Super. Thanks for all of this. Will post how it goes. It is to try and help my sweetie who has constant pain from nerve damage as a result of a not exactly 100% ankle surgery, and we are slowly figuring out how to reconnect her nerve damage. In the mean time, anything to help calm the pain would be the ticket.