My WM-703C didn't come with a battery cover for the gumstick battery compartment, so I modeled a new one for it. A 0.2mm nozzle is kind of mandatory, unless you want to do a lot of post processing. My covers fit without any sanding, cutting etc, but you might need to tweak your printer settings as the latch needs really good layer adhesion to be durable.
Printed on a Bambu P1S with 0.2mm nozzle and support interface filament for the rear tab. I'm not sure if it would print well without interface filament, because it's all on such a small scale. If you don't have an AMS you can do it like I used to: Add a pause G-code, manually swap filaments (PLA -> PETG or the other way around) and then hit resume on the printer! The fit is absolutely perfect. I'm very happy with the result.