Interestingly enough I used play-do models for letters when I taught in a special-ed class a few years back. That was for a multi-sensory approach as opposed to Davis ´ symbol mastery. It was useful for me and as Davis ´ himself says ... it causes no harm. It ´s great fun at any rate. The main point is that there is no conclusive evidence as yet to support his theories or methods and by that I mean published results in reputable journals.
I would be more than happy to borrow some of his techniques for creativity in the classroom but would not use them to sort dyslexia since there is not much teaching and honing of the skills of reading. It ´s an alternative approach and should be used in conjunction with other more established techniques.
The biggest teaching tip from his work comes from the thinking of dyslexia as a gift and if the students can go with that, then it has helped.
IMHO
How would you introduce it to your student?