I needed a solution to carry more juice for my camera but most of the time i don't really need a full or half cage to mount my npf battery plate so i recreated the mount rail and plate to make it more compact. now the camera grip still feels natural while still having the option to use my 550-900 battery pack if need be.
If you want to make the same setup you will need to find the right dummy battery for your camera. My A7Sii fortunately has a version of the dummy battery that connects to usb-A.

FlashForge

Creator Pro

No

Yes

0.2

100

Printed with full infill on PETG for maximum strength