Hello, I am currently working on the Ferrero and Manu Maugain methods. On the latter, there are a few pages on the ricochet and the bellows shake. Could someone tell me more about it? What are these techniques? I could see some videos of it on the internet but the technique and the way of working don't seem clear to me... Also, when is it used? Are there some kinds of pieces more appropriate than others to practice it? Thanks!