I just ran across this interesting idea of using an electric toothbrush as a miniature "orbital sander." This idea could easily be adapted for metal working by substituting abrasive cloth for sandpaper.
The original post is here:
http://tips.woodmagazine.com/sanding-sharpening/4-out-of-5-dentists-recommend-this-detail-sander/
The original post is here:
http://tips.woodmagazine.com/sanding-sharpening/4-out-of-5-dentists-recommend-this-detail-sander/