I spend a substantial amount of cash with mobile solutions. Their CA glue is top notch!The speaker adapter material is 1/4” ABS. I simply traced a Scosche adapter that I already had then used a hole saw for the speaker. Just so happened that the needed HAT hole dimension is the same exact dimension of a 3” hole saw.
I had just received my Mobile Solutions CA glue set so I used it to attach the baffles for now. The baffles will actually be sandwiched between the door and the adapters. View attachment 292819