BOM_parse.py

import FreeCADGui as Gui

a = Gui.Selection.getSelection()

for i in a:
    xl = i.Shape.BoundBox.XLength/25.4
    yl = i.Shape.BoundBox.YLength/25.4
    zl = i.Shape.BoundBox.ZLength/25.4
    print i.Label +", x="+ str(xl)+" , y="+str(yl)+" , z="+str(zl)


#parse groups
g  = Gui.Selection.getSelection()

for l in g:
    if l.TypeId == 'App::DocumentObjectGroup':
        print l.Label

        for i in l.Group:
            xl = i.Shape.BoundBox.XLength/25.4
            yl = i.Shape.BoundBox.YLength/25.4
            zl = i.Shape.BoundBox.ZLength/25.4
            print i.Label +", x="+ str(xl)+" , y="+str(yl)+" , z="+str(zl)

    if l.TypeId <> 'App::DocumentObjectGroup':
        xl = l.Shape.BoundBox.XLength/25.4
        yl = l.Shape.BoundBox.YLength/25.4
        zl = l.Shape.BoundBox.ZLength/25.4
        print i.Label +", x="+ str(xl)+" , y="+str(yl)+" , z="+str(zl)