diff --git a/libsrc/csg/csgeom.cpp b/libsrc/csg/csgeom.cpp
index cc3e4464..e1ada634 100644
--- a/libsrc/csg/csgeom.cpp
+++ b/libsrc/csg/csgeom.cpp
@@ -176,9 +176,8 @@ namespace netgen
     
     solids.DeleteAll ();
 
-    for (int i = 0; i < splinecurves2d.Size(); i++)
-      delete splinecurves2d[i];
     splinecurves2d.DeleteAll();
+    splinecurves3d.DeleteAll();
     
     /*
     for (int i = 0; i < surfaces.Size(); i++)
@@ -712,24 +711,24 @@ namespace netgen
 
 
 
-  void CSGeometry :: SetSplineCurve (const char * name, SplineGeometry<2> * spl)
+  void CSGeometry :: SetSplineCurve (const char * name, shared_ptr<SplineGeometry<2>> spl)
   {
     splinecurves2d.Set(name,spl);
   }
-  void CSGeometry :: SetSplineCurve (const char * name, SplineGeometry<3> * spl)
+  void CSGeometry :: SetSplineCurve (const char * name, shared_ptr<SplineGeometry<3>> spl)
   {
     splinecurves3d.Set(name,spl);
   }
 
 
-  const SplineGeometry<2> * CSGeometry :: GetSplineCurve2d (const string & name) const
+  shared_ptr<SplineGeometry<2>> CSGeometry :: GetSplineCurve2d (const string & name) const
   {
     if (splinecurves2d.Used(name))
       return splinecurves2d[name];
     else
       return NULL;
   }
-  const SplineGeometry<3> * CSGeometry :: GetSplineCurve3d (const string & name) const
+  shared_ptr<SplineGeometry<3>> CSGeometry :: GetSplineCurve3d (const string & name) const
   {
     if (splinecurves3d.Used(name))
       return splinecurves3d[name];
diff --git a/libsrc/csg/csgeom.hpp b/libsrc/csg/csgeom.hpp
index 35453b30..17d0a3d9 100644
--- a/libsrc/csg/csgeom.hpp
+++ b/libsrc/csg/csgeom.hpp
@@ -115,9 +115,9 @@ namespace netgen
     SymbolTable<Solid*> solids;
 
     /// all 2d splinecurves
-    SymbolTable< SplineGeometry<2>* > splinecurves2d;
+    SymbolTable<shared_ptr<SplineGeometry<2>>> splinecurves2d;
     /// all 3d splinecurves
-    SymbolTable< SplineGeometry<3>* > splinecurves3d;
+    SymbolTable<shared_ptr<SplineGeometry<3>>> splinecurves3d;
 
     /// all top level objects: solids and surfaces
     NgArray<TopLevelObject*> toplevelobjects;
@@ -232,10 +232,10 @@ namespace netgen
     const SymbolTable<Solid*> & GetSolids () const { return solids; }
 
 
-    void SetSplineCurve (const char * name, SplineGeometry<2> * spl);
-    void SetSplineCurve (const char * name, SplineGeometry<3> * spl);
-    const SplineGeometry<2> * GetSplineCurve2d (const string & name) const;
-    const SplineGeometry<3> * GetSplineCurve3d (const string & name) const;
+    void SetSplineCurve (const char * name, shared_ptr<SplineGeometry<2>> spl);
+    void SetSplineCurve (const char * name, shared_ptr<SplineGeometry<3>> spl);
+    shared_ptr<SplineGeometry<2>> GetSplineCurve2d (const string & name) const;
+    shared_ptr<SplineGeometry<3>> GetSplineCurve3d (const string & name) const;
 
     void DoArchive(Archive& archive) override;
     
diff --git a/libsrc/csg/csgparser.cpp b/libsrc/csg/csgparser.cpp
index 4e3c1786..05c1bdcd 100644
--- a/libsrc/csg/csgparser.cpp
+++ b/libsrc/csg/csgparser.cpp
@@ -511,8 +511,8 @@ namespace netgen
 		  break;
 		}
 	      
-	      Primitive * nprim = new Extrusion(*(geom->GetSplineCurve3d(epath)),
-						*(geom->GetSplineCurve2d(profile)),
+	      Primitive * nprim = new Extrusion(geom->GetSplineCurve3d(epath),
+						geom->GetSplineCurve2d(profile),
 						z_dir);
 	      geom->AddSurfaces (nprim);
 	      return new Solid(nprim);
@@ -1186,7 +1186,7 @@ namespace netgen
 		ParseChar (scan, '=');
 		ParseChar (scan, '(');
 		
-		SplineGeometry<2> * newspline = new SplineGeometry<2>;
+		auto newspline = make_shared<SplineGeometry<2>>();
 		// newspline->CSGLoad(scan);
 		LoadSpline (*newspline, scan);
 
@@ -1212,7 +1212,7 @@ namespace netgen
 		ParseChar (scan, '=');
 		ParseChar (scan, '(');
 		
-		SplineGeometry<3> * newspline = new SplineGeometry<3>;
+		auto newspline = make_shared<SplineGeometry<3>>();
 		// newspline->CSGLoad(scan);
 		LoadSpline (*newspline, scan);
 
diff --git a/libsrc/csg/extrusion.cpp b/libsrc/csg/extrusion.cpp
index c5518ab8..cb1466cb 100644
--- a/libsrc/csg/extrusion.cpp
+++ b/libsrc/csg/extrusion.cpp
@@ -658,18 +658,18 @@ namespace netgen
   }
   
 
-  Extrusion :: Extrusion(const SplineGeometry<3> & path_in,
-			 const SplineGeometry<2> & profile_in,
+  Extrusion :: Extrusion(shared_ptr<SplineGeometry<3>> path_in,
+			 shared_ptr<SplineGeometry<2>> profile_in,
 			 const Vec<3> & z_dir) :
-    path(&path_in), profile(&profile_in), z_direction(z_dir)
+    path(path_in), profile(profile_in), z_direction(z_dir)
   {
     surfaceactive.SetSize(0);
     surfaceids.SetSize(0);
 
     for(int j=0; j<profile->GetNSplines(); j++)
       {
-	ExtrusionFace * face = new ExtrusionFace(&((*profile).GetSpline(j)),
-						 path,
+	ExtrusionFace * face = new ExtrusionFace(&(profile->GetSpline(j)),
+						 path.get(),
 						 z_direction);
 	faces.Append(face);
 	surfaceactive.Append(true);
diff --git a/libsrc/csg/extrusion.hpp b/libsrc/csg/extrusion.hpp
index e9680eff..a2c8a084 100644
--- a/libsrc/csg/extrusion.hpp
+++ b/libsrc/csg/extrusion.hpp
@@ -121,8 +121,8 @@ namespace netgen
   class Extrusion : public Primitive
   {
   private:
-    const SplineGeometry<3>* path;
-    const SplineGeometry<2>* profile; // closed, clockwise oriented curve
+    shared_ptr<SplineGeometry<3>> path;
+    shared_ptr<SplineGeometry<2>> profile; // closed, clockwise oriented curve
 
     Vec<3> z_direction;
 
@@ -131,8 +131,8 @@ namespace netgen
     mutable int latestfacenum;
 
   public:
-    Extrusion(const SplineGeometry<3> & path_in,
-	      const SplineGeometry<2> & profile_in,
+    Extrusion(shared_ptr<SplineGeometry<3>> path_in,
+	      shared_ptr<SplineGeometry<2>> profile_in,
 	      const Vec<3> & z_dir);
     // default constructor for archive
     Extrusion() {}
diff --git a/libsrc/csg/python_csg.cpp b/libsrc/csg/python_csg.cpp
index 0954b2d6..112c88a9 100644
--- a/libsrc/csg/python_csg.cpp
+++ b/libsrc/csg/python_csg.cpp
@@ -170,7 +170,8 @@ namespace netgen
 
 DLL_HEADER void ExportCSG(py::module &m)
 {
-  py::class_<SplineGeometry<2>> (m, "SplineCurve2d")
+  py::class_<SplineGeometry<2>, shared_ptr<SplineGeometry<2>>>
+    (m, "SplineCurve2d")
     .def(py::init<>())
     .def ("AddPoint", FunctionPointer
           ([] (SplineGeometry<2> & self, double x, double y)
@@ -329,8 +330,8 @@ DLL_HEADER void ExportCSG(py::module &m)
                                            Solid * sol = new Solid(rev);
                                            return make_shared<SPSolid> (sol);
                                          }));
-  m.def ("Extrusion", FunctionPointer([](const SplineGeometry<3> & path,
-					 const SplineGeometry<2> & profile,
+  m.def ("Extrusion", FunctionPointer([](shared_ptr<SplineGeometry<3>> path,
+					 shared_ptr<SplineGeometry<2>> profile,
 					 Vec<3> n)
                                          {
                                            Extrusion * extr = new Extrusion (path,profile,n);