Been meaning to post this for a while. I adapted the phone mount for a friend as we were having difficulty sourcing the thread insert for the tripod so I adapted the model to include a thread in the print.
I've also flattened the models to the build plate.
Just print off all the separate items and then I found running a tap into the hole and inserting M3 (from memory) to hold things together works just fine. Find a suitable spring or use a rubber band to hold the phone in place if you so desire.