There was an unused mounting spot on the back of the frame, I think maybe for a VTX antenna, but since I used a different mount for the lollipop, I figured I could put a buzzer there. 

I printed in TPU and used 2mm screws to affix it to the frame. You can tighten it up a bit using horizontal hole expansion in your slicer. It is sized to be printed in a rigid material.