This is a parametric OpenSCAD design for a powerbrick holder. It should fit any reasonably-sized power brick using "Europlug" plugs, which are standard in Europe.
You can use the attached OpenSCAD script to adjust your standard Gridfinity parameters (such as configuring holes for magnets or the size) and changing the rotation and amount of powerbrick holes. To use this script, you should place a copy of the gridfinity-rebuilt-openscad repository next to the openscad file and name it “gridfinity-rebuilt”. I used commit `fd4db5aa9f5c72f1b7b8fc2311369b5ca39c664c`.