Reworked the command line interface based on the current state

of the upstream.
Thanks @alexrj, @lordofhyphens for the original code of slic3r.cpp

src/libslic3r/Format/OBJ.cpp

@@ -115,4 +115,23 @@ bool load_obj(const char *path, Model *model, const char *object_name_in)
     return true;
 }
 
+bool store_obj(const char *path, TriangleMesh *mesh)
+{
+    //FIXME returning false even if write failed.
+    mesh->WriteOBJFile(path);
+    return true;
+}
+
+bool store_obj(const char *path, ModelObject *model_object)
+{
+    TriangleMesh mesh = model_object->mesh();
+    return store_obj(path, &mesh);
+}
+
+bool store_obj(const char *path, Model *model)
+{
+    TriangleMesh mesh = model->mesh();
+    return store_obj(path, &mesh);
+}
+
 }; // namespace Slic3r

src/libslic3r/Format/OBJ.hpp

@@ -9,6 +9,10 @@ class Model;
 // Load an OBJ file into a provided model.
 extern bool load_obj(const char *path, Model *model, const char *object_name = nullptr);
 
+extern bool store_obj(const char *path, TriangleMesh *mesh);
+extern bool store_obj(const char *path, ModelObject *model);
+extern bool store_obj(const char *path, Model *model);
+
 }; // namespace Slic3r
 
 #endif /* slic3r_Format_OBJ_hpp_ */

src/libslic3r/Format/STL.cpp

@@ -55,4 +55,10 @@ bool store_stl(const char *path, ModelObject *model_object, bool binary)
     return store_stl(path, &mesh, binary);
 }
 
+bool store_stl(const char *path, Model *model, bool binary)
+{
+    TriangleMesh mesh = model->mesh();
+    return store_stl(path, &mesh, binary);
+}
+
 }; // namespace Slic3r

src/libslic3r/Format/STL.hpp

@@ -11,6 +11,7 @@ extern bool load_stl(const char *path, Model *model, const char *object_name = n
 
 extern bool store_stl(const char *path, TriangleMesh *mesh, bool binary);
 extern bool store_stl(const char *path, ModelObject *model_object, bool binary);
+extern bool store_stl(const char *path, Model *model, bool binary);
 
 }; // namespace Slic3r