The updated end cap now does not have the passthrough holes in the center that you see glued closed on the original blue printed model that is shown in the pictures. (the screw holes are still on it)
I have included the file for the original end cap as well because you could always have a couple wires coming out to power something else like a rc car battery pigtail or something.
If the main 3MF (the one with the battery in the picture) is too tight, try the 2nd (with the screenshot of the sliced project)
All the usb parts required are linked in the pdf.