Looks good, but I've got a couple of questions:
1) How stable is it once mounted on the strap? Does it flop around a lot?
2) Are there any plans to add the little hex indention to the one side (preferably the inside) to hold the nut? This is how most screw mounts from GoPro actually come so the nut doesn't spin when tightening. I've attached a picture as an example.
3) Will this fit the original GoPro Hero dive housing with the larger, flat glass lens?
I think this is a great solution since it puts the camera on the side and avoids most of the bubbles from the regulator.