"The Supportstructure was heavy, but that could be also my fault (i test currently a new version of cura)"

...uhm, you can print every piece of the holders without support, even the one with that leash facing outside. thats why i flipped that one 90° upside. there is no need for support, because the outlines come first, and the rest is just filled between them..

...that's why i put this comment into the description:
The mounts should fit to most outlets available in Germany, for all other they can be modified through the scad file. All mounts are contained in one single scad file and can be easily modified with shared variables.

i know, some sockets are rather bulky and malformed, but the mounts match on the most socket strips, so even if it does not exactly match, you don't have to throw them into trash, but use them for another strip instead. usually i need lots of them^^