You can make one with an old sawzall blade. grind the teeth off, make it about 3" long, make a bend on the end then it can be round, angled or square across. Each shape will give you a different pattern. Make a handle with a hole to accommodate the size and put in a set or thumb screw and you have a chatter tool. Here is a link that has pictures plus directions similar to mine. I made one in about an hour. Hilton Handcraft - Shopmade Chatter Tool