Quick model of a wall mount for the parkside 12V Battery.

Model is rough, some of the radiuses and angles I have eyballed. - but does the job. 

Can be printed rough - 0.24mm even 0.3mm layer height.

Model is spaced so that the holders can be butted together, and you still have enough space for loading the batteries, even the 4Ah ones. Obviously it fits the 2Ah batteries too. 

Printed in PLA, 3 walls - probably overkill