AC800W / Rollei 410 Actioncamera case backdoor with huge battery

This is a replacement for the backdoor of the Rollei 410 / Magnion AC800W case to have a 3x18650 LiIon Battery for longer battery life.

Update: I have added the replacement "battery" design, which is a connector to get the power inside the camera and the cable out. Also added the individual parts.

Update2: had a prototype printed and found out that there is the need for some space to get the cables out of the camera and back to the new battery.