The new wall holder:
Sine my wall is 27cm sandstone (used to be a garage, they seem to have added this later) and then 8cm brick I drilled through the whole wall and fastened the top with 8mm rods. This thing is only coming down if the whole wall comes down now.
Ignore the two empty holes… I miscalculated and had two make two new holes with hand tools, like a caveman… In the plans I uploaded I fixed the error.
Test:
The arm fits (not fastened, just easily chilling there), there is now also a support beam (don`t think I’d really need it, but better save than sorry).
The support beam:
Two parts, glued together, including space for bearings (as all the other parts).
And finally, the dxf. I am really happy with how it turned out. There are annotations, but you can’t see them in Estlcam. Use LibreCAD or AutoCAD to read those. 
Boom Arm V2 Slim.dxf (199.1 KB)
/edit: Now with video as well:
