Deform Problems (Rigify)

For those of you who could help me,
I started on a character yesterday comprised of low poly rocks (I’m making a golem/elemental of sorts), and am trying to figure out how to rig the individual pieces without deforming anything (I want the rocks to retain their shape). The pictures below show the original and the deformation:

Any assistance would be greatly appreciated,

For each bone set the weighting to 1 for the whole rock.

Great, thanks mate

Do I need to do that with weight painting?