This is simple hecht accumulator adapter. My battery is model 1246, but it can be probably used for all of them.
There are two files. One with hole and one without hole. It's for cables in the back.

Print
layer height: 0.2 or 0.25 - it should fit both way, but for faster printing I used 0.25
support: organic
material: PLA or PETG - I recommend PETG for durability
infill: 15% - cubic
perimeters: 3

Holes
They are made for M3 screws. I recommend Allen screw, but it can be used with anything. 

Enjoy printing!