This free stutter [book](https://www.freestutteringbooks.com/uploads/3/2/1/1/32111425/dr._bob_bodenhamer.pdf) (2002) from Bodenhamer is recommended. It approaches visualization exercises that you learn from a hypnotherapist, NLP therapist or Neuro-Semantics therapist. Note, there is also a 2005 version of that book on Amazon called 'Mastering Blocking'. It's the same book with 100 more pages and better diagrams.