I wanted this to surface/side mount a Anderson plug without visible mounting screws.  you can mount the Anderson plug to lower mount first (with 2 recessed mounting holes) then attach the entire assembly to surface with M4 screws or up to you how to use the mounting holes associated with the Anderson plug itself.  Cover slides on or can be clipped in place and use a optional m4 screw to lock cover, you will need to self thread it into place.

I have resolution set to 0.28 extra draft up to you if you want to increase resolution. no supports necessary I have file set to use a brim.

Post a pic I would love to see your print.