They repeatedly hit the participants» right hands gently with a small hammer while replacing the natural sound of the hammer against the skin with the sound of a hammer hitting a piece of marble.
We really scratched and gauged the top A TON using our high tech skilled DIY'er tools: a piece of sandpaper to rough things up, a baggie of screws and nails (just hit the baggie on the counter surface), and a screw driver and hammer to dent it.