What about asking if he would record something for you? So that you would not only have something personalised from him, but also that you could hear his voice whenever you wanted to.

For example, (take whatever seems appropriate and discard the rest):
How much progress you've made. Remind you of all the things you've learned, the coping skills, the grounding techniques. He could say what he feels about the time you've worked together. Maybe a summary of why he believes in you, that you will be okay. That it's okay to grieve for him and for the loss of the therapy relationship (I had difficulty with this myself and it would have been helpful to have been told it was a natural and normal thing to do).

Of course if he weren't willing to record this, he could write it down for you to read.

Hope some of this might help.

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