Phantom 2 spacer for H3-3D

One more spacer for mounting an H3-3D on a first series Phantom 2. Found already available designs to be unnecessarily heavy or imprecise, so redesigned one with less material.

Thickness 3mm, which is thin enough not to need leg spacers at least on my friend's set I have here. M3x8 motor screws fit well for attaching the lot.