diff --git a/src/ifcwrap/IfcGeomWrapper.i b/src/ifcwrap/IfcGeomWrapper.i
index 099615fa18..08e62609e6 100644
--- a/src/ifcwrap/IfcGeomWrapper.i
+++ b/src/ifcwrap/IfcGeomWrapper.i
@@ -58,6 +58,15 @@
 	}
 }
 
+%newobject IfcGeom::ConversionResultShape::halfspaces;
+%newobject IfcGeom::ConversionResultShape::box;
+%newobject IfcGeom::ConversionResultShape::solid;
+%newobject IfcGeom::ConversionResultShape::add;
+%newobject IfcGeom::ConversionResultShape::subtract;
+%newobject IfcGeom::ConversionResultShape::intersect;
+%newobject IfcGeom::ConversionResultShape::moved;
+%newobject nary_union;
+
 %include "../ifcgeom/ifc_geom_api.h"
 %include "../ifcgeom/Converter.h"
 %include "../ifcgeom/ConversionResult.h"
@@ -631,16 +640,48 @@ struct ShapeRTTI : public boost::static_visitor<PyObject*>
 %template(OpaqueCoordinate_3) IfcGeom::OpaqueCoordinate<3>;
 %template(OpaqueCoordinate_4) IfcGeom::OpaqueCoordinate<4>;
 
-%{
-	#include "../ifcgeom/kernels/cgal/CgalConversionResult.h"
-%}
-
 %inline %{
 	std::shared_ptr<IfcGeom::OpaqueNumber> create_epeck(int i) {
 		return std::make_shared<ifcopenshell::geometry::NumberEpeck>(i);
 	}
 %}
 
+%inline %{
+	IfcGeom::ConversionResultShape* nary_union(PyObject* sequence) {
+		CGAL::Nef_nary_union_3< CGAL::Nef_polyhedron_3<Kernel_> > accum;
+		for(Py_ssize_t i = 0; i < PySequence_Size(sequence); ++i) {
+			PyObject* element = PySequence_GetItem(sequence, i);
+			void* argp1 = nullptr;
+			auto res1 = SWIG_ConvertPtr(element, &argp1, SWIGTYPE_p_IfcGeom__ConversionResultShape, 0);
+			if (SWIG_IsOK(res1)) {
+				auto arg1 = reinterpret_cast<IfcGeom::ConversionResultShape*>(argp1);
+				auto cgs = dynamic_cast<ifcopenshell::geometry::CgalShape*>(arg1);
+				if (cgs) {
+					accum.add_polyhedron(cgs->nef());
+				}
+			}
+		}
+		return new ifcopenshell::geometry::CgalShape(accum.get_union());
+	}
+%}
+
+%extend IfcGeom::ConversionResultShape {
+	std::string serialize_obj() {
+		std::ostringstream result;
+		auto cgs = dynamic_cast<ifcopenshell::geometry::CgalShape*>(self);
+		if (cgs) {
+			write_to_obj(cgs->nef(), result, std::numeric_limits<size_t>::max());
+		}		
+		return result.str();
+	}
+
+	std::string serialize() {
+		std::string result;
+		ifcopenshell::geometry::taxonomy::matrix4 iden;
+		$self->Serialize(iden, result);
+		return result;
+	}
+}
 
 %naturalvar svgfill::polygon_2::boundary;
 %naturalvar svgfill::polygon_2::inner_boundaries;
diff --git a/src/ifcwrap/IfcPython.i b/src/ifcwrap/IfcPython.i
index c5abadb467..a35b97c4d3 100644
--- a/src/ifcwrap/IfcPython.i
+++ b/src/ifcwrap/IfcPython.i
@@ -139,6 +139,10 @@
 	#include "../ifcgeom/ConversionResult.h"
 
 	#include "../svgfill/src/svgfill.h"
+
+#ifdef IFOPSH_WITH_CGAL
+	#include "../ifcgeom/kernels/cgal/CgalConversionResult.h"
+#endif
 %}
 
 // Create docstrings for generated python code.
diff --git a/src/ifcwrap/utils/type_conversion.i b/src/ifcwrap/utils/type_conversion.i
index b496ae0caa..67843cfcd2 100644
--- a/src/ifcwrap/utils/type_conversion.i
+++ b/src/ifcwrap/utils/type_conversion.i
@@ -138,7 +138,9 @@
 	PyObject* pythonize(const IfcParse::inverse_attribute* t) { return SWIG_NewPointerObj(SWIG_as_voidptr(t), SWIGTYPE_p_IfcParse__inverse_attribute, 0); }
 	PyObject* pythonize(const IfcParse::entity* t)      { return SWIG_NewPointerObj(SWIG_as_voidptr(t), SWIGTYPE_p_IfcParse__entity, 0);             }
 	PyObject* pythonize(const IfcParse::declaration* t) { return SWIG_NewPointerObj(SWIG_as_voidptr(t), declaration_type_to_swig(t), 0);             }
-	PyObject* pythonize(const IfcGeom::ConversionResultShape* t) { return SWIG_NewPointerObj(SWIG_as_voidptr(t), SWIGTYPE_p_IfcGeom__ConversionResultShape, 0); }
+	// @nb ownership
+	PyObject* pythonize(const IfcGeom::ConversionResultShape* t) { return SWIG_NewPointerObj(SWIG_as_voidptr(t), SWIGTYPE_p_IfcGeom__ConversionResultShape, SWIG_POINTER_OWN); }
+	// PyObject* pythonize(const IfcGeom::ConversionResultShape* t) { return SWIG_NewPointerObj(SWIG_as_voidptr(t), SWIGTYPE_p_IfcGeom__ConversionResultShape, 0); }
 	// NB: This cannot be temporary as a Python object is constructed from a pointer to the address of this object
 	// PyObject* pythonize(const IfcGeom::Material& t)     { return SWIG_NewPointerObj(SWIG_as_voidptr(&t), SWIGTYPE_p_IfcGeom__Material, 0);           }
 	
diff --git a/src/ifcwrap/utils/typemaps_in.i b/src/ifcwrap/utils/typemaps_in.i
index b8a95edec2..90a6a9fec2 100644
--- a/src/ifcwrap/utils/typemaps_in.i
+++ b/src/ifcwrap/utils/typemaps_in.i
@@ -317,4 +317,58 @@ CREATE_VECTOR_TYPEMAP_IN(std::string, STRING, str)
 
 CREATE_OPTIONAL_TYPEMAP_IN(int, integer, int)
 CREATE_OPTIONAL_TYPEMAP_IN(double, real, float)
-CREATE_OPTIONAL_TYPEMAP_IN(std::string, string, str)
\ No newline at end of file
+CREATE_OPTIONAL_TYPEMAP_IN(std::string, string, str)
+
+%{
+	bool check_aggregate_of_swig_type(PyObject* aggregate, swig_type_info* type_obj) {
+		if (!PySequence_Check(aggregate)) return false;
+		for(Py_ssize_t i = 0; i < PySequence_Size(aggregate); ++i) {
+			PyObject* element = PySequence_GetItem(aggregate, i);
+			
+			bool b = true;
+			void* argp1 = nullptr;
+			auto res1 = SWIG_ConvertPtr(element, &argp1, type_obj, 0);
+			if (!SWIG_IsOK(res1)) {
+				b = false;
+			}
+			
+			Py_DECREF(element);
+			if (!b) {
+				return false;
+			}
+		}
+		return true;		
+	}
+
+	template <typename T>
+	std::vector<T> python_sequence_as_swig_object_vector(PyObject* aggregate, swig_type_info* type_obj) {
+		std::vector<T> result_vector;
+		result_vector.reserve(PySequence_Size(aggregate));
+		for(Py_ssize_t i = 0; i < PySequence_Size(aggregate); ++i) {
+			PyObject* element = PySequence_GetItem(aggregate, i);
+			void* argp1 = nullptr;
+			auto res1 = SWIG_ConvertPtr(element, &argp1, type_obj, 0);
+			if (SWIG_IsOK(res1)) {
+				auto arg1 = reinterpret_cast<IfcGeom::OpaqueCoordinate<4>*>(argp1);
+				result_vector.push_back(*arg1);
+			}
+		}
+		return result_vector;
+	}
+%}
+
+%typemap(typecheck,precedence=SWIG_TYPECHECK_INTEGER) const std::vector<IfcGeom::OpaqueCoordinate<4>>& {
+	$1 = check_aggregate_of_swig_type($input, SWIGTYPE_p_IfcGeom__OpaqueCoordinateT_4_t) ? 1 : 0;
+}
+%typemap(arginit) const std::vector<IfcGeom::OpaqueCoordinate<4>>& {
+	$1 = new std::vector<IfcGeom::OpaqueCoordinate<4>>();
+}
+%typemap(in) const std::vector<IfcGeom::OpaqueCoordinate<4>>& {
+	if (!check_aggregate_of_swig_type($input, SWIGTYPE_p_IfcGeom__OpaqueCoordinateT_4_t)) {
+		SWIG_exception(SWIG_TypeError, "");
+	}
+	*$1 = python_sequence_as_swig_object_vector<IfcGeom::OpaqueCoordinate<4>>($input, SWIGTYPE_p_IfcGeom__OpaqueCoordinateT_4_t);
+}
+%typemap(freearg) const std::vector<IfcGeom::OpaqueCoordinate<4>>& {
+	delete $1;
+}