You group some objekts as an example 2 magfields an then press E to rotate the group around the x,y and z axis.

I mean, about any origin you want

Sry my english is not the best wat do you mean with about any origin?

By origin I mean in the mathematical sense, i.e. I choose what the origin is = I choose what point (x,y,z)=(0,0,0) is.
(So in this case, I choose the origin as the centre of an arbitrary object that I will delete later.)
If I select two magfields some distance away, then the rotate tool appears at the 2nd object I selected. If I then rotate, the 2nd magfield rotates around itself, while the 1st magfield rotates around the 2nd object too. If I do a 180 rotation, then the 1st magfield will be pivoted until it's on the opposite side of the 2nd magfield. If I hold 'alt' to clone them, then I will have a perfect reflection on opposite sides of the 2nd magfield.
EDIT: Well, it's only a reflection in this case if the magfield is symmetric in the appropriate ways; Also, this doesn't seem to work when I try to group with a health pack for some reason :/

Hi Rakurai, excellent solution! Yeah, so far as I'm aware there's no more convenient way to do this with UE4 unfortunately, but this is a pretty neat method anyway.