Liferider has a post from back a couple years.. Modify a electric carving knife, (cut most of the knife off) attach pieces from paint stir sticks . IIRC wrap with scotch bright . And go after it. I also seen a video from a guy that modified a multi cutter blade and attached pieces of bondo spatulas to do essentially the same thing. He had a few different shapes made for specific areas... like around the spark plug area.