Axes systems in FreeCAD
I more or less finished an axes system for the Arch module. It is a simple, 1-dimension axes system. You can specify the length of the axes, the size of the numbering bubble, and the numbering style (1,2,3,... or A,B,C, etc. Several styles available) directly via the properties. Then, via edit mode (double-clicking on the object in the Tree view), you can refine the whole axes sequence, by adding and removing axes, and changing the interval distance and angle of each axis. They are also movable and rotationable, so you can create very complex axes systems, which are totally snappable, including to the intersections.
Later on I plan to use them for laying out the levels of a multi-floor construction too, creating true 3-dimension systems, and find a way to have structural elements bound to them, so you can parametrically stretch buildings only by modifying their axes systems.