This is my take on an insert for the “useless” case that Gopro included with Gopro 11 and previous versions.

This is set up to hold the following:

1. GoPro 10 to 12 with a lens mod on. (it will work without the lens mode)

4 Batteries (10 to 12 extended versions)

and slot of accessories

I'm planning to do other versions that will fit various 3d printed boxes