there is a general toolbar available in core FreeCAD (meaning: in all workbenches) called "Structure" and which allows to create "some" of core FreeCAD's structures: Std_Part, Std_Group, Std_Link, and Link_Group. I find this sub-optimal to say the least, unfortunately it is defined in C++ and I haven't been able to change it.
So I propose a new "Structures" toolbar, made in Python, and also available in core FreeCAD (all workbenches) and which would create the following core structures:
- Part
- Body
- Sketch
- Datum Point
- Datum Axis
- Datum Plane
- Datum LCS
Incidentally, we could also change the icons of datum objects, I think that the original icons are not very explicit and look more like regular line/rectangle: