Carrara sometimes crashes on my set-up also & there are some shortcommings but it is workable. First export your foot (not the whole figure) as a wavefront object. Import into Carrara and then enlarge 1000%. The create a spline object to form around the foot. Or, use the mesh from the foot & modify it in the mesh modeler (add thikness, build new polys, etc) to crete the shoe.