Summary

This enables you to charge or balance this type of battery outside of the car. This may be necessary, if the BMS shows an undervoltage error, but the voltage is not dangerously low yet

Post-Printing

Remove all supports
Bore out the mounting holes in the small plugs to 2.5mm.
Widen the slot in the small plugs to 2.5mm as well (you can use the same drill for that)
Connect and remove every small plug a few times to test the fit and loosen it a bit
Cut a small piece of pure nickel strip (0.2x8mm) for each small plug, insert it and bend it the obvious way.
Bend the corners at the back so the nickel strip won't come lose and it can fit inside the mounting board. Then solder a wire to the nickel.
Insert the small plugs into the mounting board
Sharpen a piece of 1.75mm 3D printing filament (I used white PLA) and insert it into the hole, fixing the small plugs to the mounting board.
Test fit the whole plug to the battery
Done!

Warning

It fits mechanically, but I have no idea about the electrical properties. Be very careful how much current you send through the plug. Big batteries are no toys.

Also note that there is no keying so far to ensure the right polarity. Be very careful!

Streetscooter Battery V6-M16 (BMZ 13INR19/66-22) Balancing Plug