diff --git a/src/ifcgeom/ConversionResult.cpp b/src/ifcgeom/ConversionResult.cpp
index 3924c5cb04..092d33feee 100644
--- a/src/ifcgeom/ConversionResult.cpp
+++ b/src/ifcgeom/ConversionResult.cpp
@@ -23,9 +23,9 @@ void IfcGeom::ConversionResult::prepend(ifcopenshell::geometry::taxonomy::matrix
 
 std::string IfcGeom::NumberNativeDouble::to_string() const {
 	std::stringstream ss;
-	ss << std::setprecision(std::numeric_limits<double>::digits10 + 1) << value_;
+	ss << std::setprecision(std::numeric_limits<double>::digits10 + 1) << value();
 	return ss.str();
 }
 
 template struct IFC_GEOM_API IfcGeom::OpaqueCoordinate<3>;
-template struct IFC_GEOM_API IfcGeom::OpaqueCoordinate<4>;
\ No newline at end of file
+template struct IFC_GEOM_API IfcGeom::OpaqueCoordinate<4>;
diff --git a/src/ifcgeom/ConversionResult.h b/src/ifcgeom/ConversionResult.h
index 1b5946f796..5ce3b19c2f 100644
--- a/src/ifcgeom/ConversionResult.h
+++ b/src/ifcgeom/ConversionResult.h
@@ -24,8 +24,18 @@
 #include "../ifcgeom/ConversionSettings.h"
 #include "../ifcgeom/taxonomy.h"
 
+#include <algorithm>
+#include <array>
+#include <cmath>
 #include <cstddef>
+#include <iomanip>
+#include <limits>
 #include <memory>
+#include <sstream>
+#include <stdexcept>
+#include <type_traits>
+#include <typeinfo>
+#include <utility>
 #include <vector>
 #include <unordered_map>
 
@@ -73,181 +83,361 @@ namespace IfcGeom {
 		class IFC_GEOM_API Triangulation;
 	}
 
-	template <typename T>
-	constexpr T add_(T a, T b) {
-		return a + b;
-	}
-
-	template <typename T>
-	constexpr T subtract_(T a, T b) {
-		return a - b;
-	}
-
-	template <typename T>
-	constexpr T multiply_(T a, T b) {
-		return a * b;
-	}
-
-	template <typename T>
-	constexpr T divide_(T a, T b) {
-		return a / b;
-	}
-
-	template <typename T>
-	constexpr bool equals_(T a, T b) {
-		return a == b;
-	}
-
-	template <typename T>
-	constexpr bool less_than_(T a, T b) {
-		return a < b;
-	}
-
-	template <typename T>
-	constexpr T negate_(T a) {
-		return -a;
-	}
-
 	class IFC_GEOM_API OpaqueNumber {
+	protected:
+		struct NumberConcept {
+			virtual ~NumberConcept() {}
+			virtual double to_double() const = 0;
+			virtual std::string to_string() const = 0;
+			virtual std::shared_ptr<const NumberConcept> add(const NumberConcept& other) const = 0;
+			virtual std::shared_ptr<const NumberConcept> subtract(const NumberConcept& other) const = 0;
+			virtual std::shared_ptr<const NumberConcept> multiply(const NumberConcept& other) const = 0;
+			virtual std::shared_ptr<const NumberConcept> divide(const NumberConcept& other) const = 0;
+			virtual std::shared_ptr<const NumberConcept> negate() const = 0;
+			virtual std::shared_ptr<const NumberConcept> from_double(double value) const = 0;
+			virtual bool equals(const NumberConcept& other) const = 0;
+			virtual bool less_than(const NumberConcept& other) const = 0;
+			virtual const std::type_info& type() const = 0;
+			virtual const void* value_ptr() const = 0;
+		};
+
+		template <typename T>
+		struct NumberModel : NumberConcept {
+			T value;
+
+			NumberModel(const T& v)
+				: value(v) {}
+
+			static const NumberModel& as_same(const NumberConcept& other) {
+				auto same = dynamic_cast<const NumberModel*>(&other);
+				if (same == nullptr) {
+					throw std::runtime_error("Incompatible opaque number types");
+				}
+				return *same;
+			}
+
+			template <typename U>
+			static auto stream_exact(std::ostream& os, const U& v, int) -> decltype(os << v.exact(), void()) {
+				os << v.exact();
+			}
+
+			template <typename U>
+			static void stream_exact(std::ostream& os, const U& v, long) {
+				if constexpr (std::is_floating_point<U>::value) {
+					os << std::setprecision(std::numeric_limits<U>::digits10 + 1);
+				}
+				os << v;
+			}
+
+			virtual double to_double() const {
+				return static_cast<double>(value);
+			}
+
+			virtual std::string to_string() const {
+				std::stringstream ss;
+				stream_exact(ss, value, 0);
+				return ss.str();
+			}
+
+			virtual std::shared_ptr<const NumberConcept> add(const NumberConcept& other) const {
+				return std::make_shared<NumberModel>(value + as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> subtract(const NumberConcept& other) const {
+				return std::make_shared<NumberModel>(value - as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> multiply(const NumberConcept& other) const {
+				return std::make_shared<NumberModel>(value * as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> divide(const NumberConcept& other) const {
+				return std::make_shared<NumberModel>(value / as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> negate() const {
+				return std::make_shared<NumberModel>(-value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> from_double(double v) const {
+				return std::make_shared<NumberModel>(T(v));
+			}
+
+			virtual bool equals(const NumberConcept& other) const {
+				return value == as_same(other).value;
+			}
+
+			virtual bool less_than(const NumberConcept& other) const {
+				return value < as_same(other).value;
+			}
+
+			virtual const std::type_info& type() const {
+				return typeid(T);
+			}
+
+			virtual const void* value_ptr() const {
+				return &value;
+			}
+		};
+
+		template <typename T>
+		struct is_shared_ptr : std::false_type {};
+
+		template <typename T>
+		struct is_shared_ptr<std::shared_ptr<T>> : std::true_type {};
+
+	private:
+		std::shared_ptr<const NumberConcept> data_;
+
+		const NumberConcept& data() const {
+			if (!data_) {
+				throw std::runtime_error("Empty opaque number");
+			}
+			return *data_;
+		}
+
+	protected:
+		OpaqueNumber(std::shared_ptr<const NumberConcept> data)
+			: data_(std::move(data)) {}
+
 	public:
-		virtual double to_double() const = 0;
-		virtual std::string to_string() const = 0;
+		OpaqueNumber() = default;
+		virtual ~OpaqueNumber() = default;
 
-		virtual ~OpaqueNumber() {}
+		template <
+			typename T,
+			typename Decayed = std::decay_t<T>,
+			typename = std::enable_if_t<!std::is_base_of<OpaqueNumber, Decayed>::value && !is_shared_ptr<Decayed>::value>>
+		explicit OpaqueNumber(T&& value)
+			: data_(std::make_shared<NumberModel<Decayed>>(std::forward<T>(value))) {}
 
-		virtual OpaqueNumber* operator+(OpaqueNumber* other) const = 0;
-		virtual OpaqueNumber* operator-(OpaqueNumber* other) const = 0;
-		virtual OpaqueNumber* operator*(OpaqueNumber* other) const = 0;
-		virtual OpaqueNumber* operator/(OpaqueNumber* other) const = 0;
-		virtual bool operator==(OpaqueNumber* other) const = 0;
-		virtual bool operator<(OpaqueNumber* other) const = 0;
-		virtual OpaqueNumber* operator-() const = 0;
-		virtual OpaqueNumber* clone() const = 0;
+		double to_double() const {
+			return data().to_double();
+		}
+
+		std::string to_string() const {
+			return data().to_string();
+		}
+
+		bool empty() const {
+			return !data_;
+		}
+
+		template <typename T>
+		const T& value_as() const {
+			if (data().type() != typeid(T)) {
+				throw std::runtime_error("Unexpected opaque number type");
+			}
+			return *static_cast<const T*>(data().value_ptr());
+		}
+
+		OpaqueNumber add(const OpaqueNumber& other) const {
+			return OpaqueNumber(data().add(other.data()));
+		}
+
+		OpaqueNumber subtract(const OpaqueNumber& other) const {
+			return OpaqueNumber(data().subtract(other.data()));
+		}
+
+		OpaqueNumber multiply(const OpaqueNumber& other) const {
+			return OpaqueNumber(data().multiply(other.data()));
+		}
+
+		OpaqueNumber divide(const OpaqueNumber& other) const {
+			return OpaqueNumber(data().divide(other.data()));
+		}
+
+		OpaqueNumber negated() const {
+			return OpaqueNumber(data().negate());
+		}
+
+		OpaqueNumber same_type(double value) const {
+			return OpaqueNumber(data().from_double(value));
+		}
+
+		bool equals(const OpaqueNumber& other) const {
+			return data().equals(other.data());
+		}
+
+		bool less_than(const OpaqueNumber& other) const {
+			return data().less_than(other.data());
+		}
+
+		OpaqueNumber operator+(const OpaqueNumber& other) const {
+			return add(other);
+		}
+
+		OpaqueNumber operator-(const OpaqueNumber& other) const {
+			return subtract(other);
+		}
+
+		OpaqueNumber operator*(const OpaqueNumber& other) const {
+			return multiply(other);
+		}
+
+		OpaqueNumber operator/(const OpaqueNumber& other) const {
+			return divide(other);
+		}
+
+		bool operator==(const OpaqueNumber& other) const {
+			return equals(other);
+		}
+
+		bool operator<(const OpaqueNumber& other) const {
+			return less_than(other);
+		}
+
+		OpaqueNumber operator-() const {
+			return negated();
+		}
 	};
 
-	// @todo this can simply be a template class, to remove the need for the NumberEpeck in CGAL kernel.
 	class IFC_GEOM_API NumberNativeDouble : public OpaqueNumber {
-	private:
-		double value_;
-
-		template <double (*Fn)(double, double)>
-		OpaqueNumber* binary_op(OpaqueNumber* other) const {
-			auto nnd = dynamic_cast<NumberNativeDouble*>(other);
-			if (nnd) {
-				return new NumberNativeDouble(Fn(value_, nnd->value_));
-			} else {
-				return nullptr;
-			}
-		}
-
-		template <bool(*Fn)(double, double)>
-		bool binary_op_bool(OpaqueNumber* other) const {
-			auto nnd = dynamic_cast<NumberNativeDouble*>(other);
-			if (nnd) {
-				return Fn(value_, nnd->value_);
-			} else {
-				return false;
-			}
-		}
-
-		template <double(*Fn)(double)>
-		OpaqueNumber* unary_op() const {
-			return new NumberNativeDouble(Fn(value_));
-		}
 	public:
 		NumberNativeDouble(double v)
-			: value_(v) {}
+			: OpaqueNumber(v) {}
 
-		virtual double to_double() const {
-			return value_;
+		double value() const {
+			return value_as<double>();
 		}
 
-		virtual std::string to_string() const;
-
-		virtual OpaqueNumber* operator+(OpaqueNumber* other) const {
-			return binary_op<add_<double>>(other);
-		}
-		virtual OpaqueNumber* operator-(OpaqueNumber* other) const {
-			return binary_op<subtract_<double>>(other);
-		}
-		virtual OpaqueNumber* operator*(OpaqueNumber* other) const {
-			return binary_op<multiply_<double>>(other);
-		}
-		virtual OpaqueNumber* operator/(OpaqueNumber* other) const {
-			return binary_op<divide_<double>>(other);
-		}
-		virtual bool operator==(OpaqueNumber* other) const {
-			return binary_op_bool<equals_<double>>(other);
-		}
-		virtual bool operator<(OpaqueNumber* other) const {
-			return binary_op_bool<less_than_<double>>(other);
-		}
-		virtual OpaqueNumber* operator-() const {
-			return unary_op<negate_<double>>();
-		}
-		virtual OpaqueNumber* clone() const {
-			return new NumberNativeDouble(value_);
-		}
+		std::string to_string() const;
 	};
 
 	template <size_t N>
 	struct IFC_GEOM_API OpaqueCoordinate {
 	private:
-		std::array<OpaqueNumber*, N> values;
+		std::array<OpaqueNumber, N> values_;
 
-		static void copy_(std::array<OpaqueNumber*, N>& dest, const std::array<OpaqueNumber*, N>& src) {
-			for (size_t i = 0; i < N; ++i) {
-				dest[i] = (src[i] != nullptr) ? src[i]->clone() : nullptr;
-			}
+		static OpaqueNumber as_number(OpaqueNumber value) {
+			return value;
 		}
+
 	public:
-		template <typename... Args>
-		OpaqueCoordinate(Args... args) {
-			static_assert(sizeof...(args) == N, "Incorrect number of arguments provided");
-			init_<0>(args...);
+#ifndef SWIG
+		template <typename... Args, typename = std::enable_if_t<sizeof...(Args) == N>>
+		OpaqueCoordinate(Args&&... args) {
+			init_<0>(std::forward<Args>(args)...);
+		}
+#endif
+
+		OpaqueCoordinate() = default;
+
+		std::size_t size() const {
+			return N;
 		}
 
-		OpaqueCoordinate() {
-			for (auto it = values.begin(); it != values.end(); ++it) {
-				*it = nullptr;
-			}
-		}
-
-		OpaqueCoordinate(const OpaqueCoordinate& other) {
-			copy_(values, other.values);
-		}
-
-		OpaqueCoordinate& operator=(const OpaqueCoordinate& other) {
-			if (this != &other) {
-				copy_(values, other.values);
-			}
-			return *this;
-		}
-
-		~OpaqueCoordinate() {
-			for (auto it = values.begin(); it != values.end(); ++it) {
-				delete *it;
-			}
-		}
-
-		OpaqueNumber* get(size_t i) const {
+		OpaqueNumber get(size_t i) const {
 			if (i >= N) {
-				return nullptr;
+				return OpaqueNumber();
 			}
-			return values[i];
+			return values_[i];
 		}
 
-		void set(size_t i, OpaqueNumber* n) {
+		double get_double(size_t i) const {
+			return get(i).to_double();
+		}
+
+		void set(size_t i, const OpaqueNumber& n) {
 			if (i < N) {
-				values[i] = n->clone();
+				values_[i] = n;
 			}
 		}
+
+		std::vector<double> to_doubles() const {
+			std::vector<double> result;
+			result.reserve(N);
+			for (const auto& value : values_) {
+				result.push_back(value.to_double());
+			}
+			return result;
+		}
+
+		OpaqueCoordinate operator-() const {
+			OpaqueCoordinate result;
+			for (size_t i = 0; i < N; ++i) {
+				result.values_[i] = values_[i].negated();
+			}
+			return result;
+		}
+
+		OpaqueCoordinate operator+(const OpaqueCoordinate& other) const {
+			OpaqueCoordinate result;
+			for (size_t i = 0; i < N; ++i) {
+				result.values_[i] = values_[i].add(other.values_[i]);
+			}
+			return result;
+		}
+
+		OpaqueCoordinate operator-(const OpaqueCoordinate& other) const {
+			OpaqueCoordinate result;
+			for (size_t i = 0; i < N; ++i) {
+				result.values_[i] = values_[i].subtract(other.values_[i]);
+			}
+			return result;
+		}
+
+		OpaqueCoordinate operator*(const OpaqueNumber& scalar) const {
+			OpaqueCoordinate result;
+			for (size_t i = 0; i < N; ++i) {
+				result.values_[i] = values_[i].multiply(scalar);
+			}
+			return result;
+		}
+
+		OpaqueCoordinate operator/(const OpaqueNumber& scalar) const {
+			OpaqueCoordinate result;
+			for (size_t i = 0; i < N; ++i) {
+				result.values_[i] = values_[i].divide(scalar);
+			}
+			return result;
+		}
+
+		OpaqueCoordinate scale(double scalar) const {
+			return *this * values_[0].same_type(scalar);
+		}
+
+		OpaqueNumber dot(const OpaqueCoordinate& other) const {
+			if constexpr (N == 0) {
+				return OpaqueNumber(0.0);
+			} else {
+				OpaqueNumber result = values_[0].multiply(other.values_[0]);
+				for (size_t i = 1; i < N; ++i) {
+					result = result.add(values_[i].multiply(other.values_[i]));
+				}
+				return result;
+			}
+		}
+
+		double norm() const {
+			return std::sqrt(dot(*this).to_double());
+		}
+
+		OpaqueCoordinate normalized() const {
+			const double length = norm();
+			if (length == 0.0) {
+				return *this;
+			}
+			return *this / values_[0].same_type(length);
+		}
+
+		OpaqueCoordinate normalized_by_max_abs() const {
+			double max_abs = 0.0;
+			for (const auto& value : values_) {
+				max_abs = (std::max)(max_abs, std::fabs(value.to_double()));
+			}
+			if (max_abs == 0.0) {
+				return *this;
+			}
+			return *this / values_[0].same_type(max_abs);
+		}
+
 	private:
-		template <size_t Index, typename... Args>
-		void init_(OpaqueNumber* value, Args... args) {
-			values[Index] = value;
+		template <size_t Index, typename Arg, typename... Args>
+		void init_(Arg&& value, Args&&... args) {
+			values_[Index] = as_number(std::forward<Arg>(value));
 			if constexpr (Index + 1 < N) {
-				init_<Index + 1>(args...);
+				init_<Index + 1>(std::forward<Args>(args)...);
 			}
 		}
 	};
@@ -271,9 +461,9 @@ namespace IfcGeom {
 		virtual std::pair<OpaqueCoordinate<3>, OpaqueCoordinate<3>> bounding_box() const = 0;
 		virtual void set_box(void* b) = 0;
 		
-		virtual OpaqueNumber* length() = 0;
-		virtual OpaqueNumber* area() = 0;
-		virtual OpaqueNumber* volume() = 0;
+		virtual OpaqueNumber length() = 0;
+		virtual OpaqueNumber area() = 0;
+		virtual OpaqueNumber volume() = 0;
 
 		virtual OpaqueCoordinate<3> position() = 0;
 		virtual OpaqueCoordinate<3> axis() = 0;
diff --git a/src/ifcgeom/IfcGeomRepresentation.cpp b/src/ifcgeom/IfcGeomRepresentation.cpp
index f0c150597e..d533adf0df 100644
--- a/src/ifcgeom/IfcGeomRepresentation.cpp
+++ b/src/ifcgeom/IfcGeomRepresentation.cpp
@@ -81,7 +81,7 @@ bool IfcGeom::Representation::BRep::calculate_surface_area(double& area) const {
 		area = 0.;
 		return false;
 	}
-	area = s->area()->to_double();
+	area = s->area().to_double();
 	return true;
 }
 
@@ -91,7 +91,7 @@ bool IfcGeom::Representation::BRep::calculate_volume(double& volume) const {
 		volume = 0.;
 		return false;
 	}
-	volume = s->volume()->to_double();
+	volume = s->volume().to_double();
 	return true;
 }
 
diff --git a/src/ifcgeom/kernels/cgal/CgalConversionResult.cpp b/src/ifcgeom/kernels/cgal/CgalConversionResult.cpp
index f8fa868946..bd9266dcf5 100644
--- a/src/ifcgeom/kernels/cgal/CgalConversionResult.cpp
+++ b/src/ifcgeom/kernels/cgal/CgalConversionResult.cpp
@@ -40,9 +40,9 @@ namespace {
 
 	OpaqueCoordinate<3> opaque_point(const cgal_point_t& p) {
 		return OpaqueCoordinate<3>(
-			new NumberType(p.cartesian(0)),
-			new NumberType(p.cartesian(1)),
-			new NumberType(p.cartesian(2))
+			NumberType(p.cartesian(0)),
+			NumberType(p.cartesian(1)),
+			NumberType(p.cartesian(2))
 		);
 	}
 
@@ -59,9 +59,9 @@ namespace {
 			throw std::runtime_error("Invalid shape type");
 		}
 		return OpaqueCoordinate<3>(
-			new NumberType(v.x() / maxval),
-			new NumberType(v.y() / maxval),
-			new NumberType(v.z() / maxval)
+			NumberType(v.x() / maxval),
+			NumberType(v.y() / maxval),
+			NumberType(v.z() / maxval)
 		);
 	}
 
@@ -71,27 +71,27 @@ namespace {
 			throw std::runtime_error("Invalid shape type");
 		}
 		return OpaqueCoordinate<4>(
-			new NumberType(p.a() / maxval),
-			new NumberType(p.b() / maxval),
-			new NumberType(p.c() / maxval),
-			new NumberType(p.d() / maxval)
+			NumberType(p.a() / maxval),
+			NumberType(p.b() / maxval),
+			NumberType(p.c() / maxval),
+			NumberType(p.d() / maxval)
 		);
 	}
 
 	cgal_plane_t plane_from_opaque(const OpaqueCoordinate<4>& p) {
 #ifdef IFOPSH_SIMPLE_KERNEL
 		return cgal_plane_t(
-			p.get(0)->to_double(),
-			p.get(1)->to_double(),
-			p.get(2)->to_double(),
-			p.get(3)->to_double()
+			p.get(0).to_double(),
+			p.get(1).to_double(),
+			p.get(2).to_double(),
+			p.get(3).to_double()
 		);
 #else
 		return cgal_plane_t(
-			static_cast<NumberEpeck*>(p.get(0))->value(),
-			static_cast<NumberEpeck*>(p.get(1))->value(),
-			static_cast<NumberEpeck*>(p.get(2))->value(),
-			static_cast<NumberEpeck*>(p.get(3))->value()
+			p.get(0).value_as<CGAL::Epeck::FT>(),
+			p.get(1).value_as<CGAL::Epeck::FT>(),
+			p.get(2).value_as<CGAL::Epeck::FT>(),
+			p.get(3).value_as<CGAL::Epeck::FT>()
 		);
 #endif
 	}
@@ -697,7 +697,7 @@ int ifcopenshell::geometry::CgalShape::num_faces() const
 	}
 }
 
-OpaqueNumber* ifcopenshell::geometry::CgalShape::CgalShape::length()
+OpaqueNumber ifcopenshell::geometry::CgalShape::CgalShape::length()
 {
 	Kernel_::FT len = 0;
 	if (is_wire()) {
@@ -711,30 +711,30 @@ OpaqueNumber* ifcopenshell::geometry::CgalShape::CgalShape::length()
 			).squared_length());
 		}
 	}
-	return new NumberType(len);
+	return NumberType(len);
 }
 
-OpaqueNumber* ifcopenshell::geometry::CgalShape::area()
+OpaqueNumber ifcopenshell::geometry::CgalShape::area()
 {
 	if (is_wire()) {
-		return new NumberType(wire_area(wire()));
+		return NumberType(wire_area(wire()));
 	}
 	if (is_point()) {
-		return new NumberType(Kernel_::FT(0));
+		return NumberType(Kernel_::FT(0));
 	}
 	auto s = poly();
 	CGAL::Polygon_mesh_processing::triangulate_faces(s);
-	return new NumberType(CGAL::Polygon_mesh_processing::area(s));
+	return NumberType(CGAL::Polygon_mesh_processing::area(s));
 }
 
-OpaqueNumber* ifcopenshell::geometry::CgalShape::volume()
+OpaqueNumber ifcopenshell::geometry::CgalShape::volume()
 {
 	if (is_point() || is_wire()) {
-		return new NumberType(Kernel_::FT(0));
+		return NumberType(Kernel_::FT(0));
 	}
 	auto s = poly();
 	CGAL::Polygon_mesh_processing::triangulate_faces(s);
-	return new NumberType(CGAL::Polygon_mesh_processing::volume(s));
+	return NumberType(CGAL::Polygon_mesh_processing::volume(s));
 }
 
 OpaqueCoordinate<3> ifcopenshell::geometry::CgalShape::position()
@@ -760,9 +760,9 @@ OpaqueCoordinate<3> ifcopenshell::geometry::CgalShape::position()
 			p[i] /= N;
 		}
 		return OpaqueCoordinate<3>(
-			new NumberType(p[0]),
-			new NumberType(p[1]),
-			new NumberType(p[2])
+			NumberType(p[0]),
+			NumberType(p[1]),
+			NumberType(p[2])
 		);
 	} else {
 		throw std::runtime_error("Invalid shape type");
@@ -1058,17 +1058,17 @@ int ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::num_faces() const
 	throw std::runtime_error("Not implemented");
 }
 
-OpaqueNumber* ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::CgalShapeHalfSpaceDecomposition::length()
+OpaqueNumber ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::CgalShapeHalfSpaceDecomposition::length()
 {
 	throw std::runtime_error("Not implemented");
 }
 
-OpaqueNumber* ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::area()
+OpaqueNumber ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::area()
 {
 	throw std::runtime_error("Not implemented");
 }
 
-OpaqueNumber* ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::volume()
+OpaqueNumber ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::volume()
 {
 	throw std::runtime_error("Not implemented");
 }
@@ -1078,9 +1078,9 @@ OpaqueCoordinate<3> ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::pos
 	if (planes_.size() == 1) {
 		auto xyz = CGAL::ORIGIN + planes_.front().d() * CGAL::Vector_3<Kernel_>(planes_.front().a(), planes_.front().b(), planes_.front().c());
 		return OpaqueCoordinate<3>(
-			new NumberType(xyz.cartesian(0)),
-			new NumberType(xyz.cartesian(1)),
-			new NumberType(xyz.cartesian(2))
+			NumberType(xyz.cartesian(0)),
+			NumberType(xyz.cartesian(1)),
+			NumberType(xyz.cartesian(2))
 		);
 	} else {
 		throw std::runtime_error("Invalid shape type");
@@ -1095,9 +1095,9 @@ OpaqueCoordinate<3> ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::axi
 		auto maxel = std::max_element(abc.begin(), abc.end());
 		auto maxval = ((-*minel) > *maxel) ? (-*minel) : *maxel;
 		return OpaqueCoordinate<3>(
-			new NumberType(planes_.front().a() / maxval),
-			new NumberType(planes_.front().b() / maxval),
-			new NumberType(planes_.front().c() / maxval)
+			NumberType(planes_.front().a() / maxval),
+			NumberType(planes_.front().b() / maxval),
+			NumberType(planes_.front().c() / maxval)
 		);
 	} else {
 		throw std::runtime_error("Invalid shape type");
@@ -1112,10 +1112,10 @@ OpaqueCoordinate<4> ifcopenshell::geometry::CgalShapeHalfSpaceDecomposition::pla
 		auto maxel = std::max_element(abc.begin(), abc.end());
 		auto maxval = ((-*minel) > *maxel) ? (-*minel) : *maxel;
 		return OpaqueCoordinate<4>(
-			new NumberType(planes_.front().a() / maxval),
-			new NumberType(planes_.front().b() / maxval),
-			new NumberType(planes_.front().c() / maxval),
-			new NumberType(planes_.front().d() / maxval)
+			NumberType(planes_.front().a() / maxval),
+			NumberType(planes_.front().b() / maxval),
+			NumberType(planes_.front().c() / maxval),
+			NumberType(planes_.front().d() / maxval)
 		);
 	} else {
 		throw std::runtime_error("Invalid shape type");
diff --git a/src/ifcgeom/kernels/cgal/CgalConversionResult.h b/src/ifcgeom/kernels/cgal/CgalConversionResult.h
index d169f5495e..f54854ac30 100644
--- a/src/ifcgeom/kernels/cgal/CgalConversionResult.h
+++ b/src/ifcgeom/kernels/cgal/CgalConversionResult.h
@@ -95,86 +95,80 @@ namespace ifcopenshell { namespace geometry {
 	using IfcGeom::OpaqueCoordinate;
 	using IfcGeom::OpaqueNumber;
 
-	using IfcGeom::add_;
-	using IfcGeom::subtract_;
-	using IfcGeom::multiply_;
-	using IfcGeom::divide_;
-	using IfcGeom::equals_;
-	using IfcGeom::less_than_;
-	using IfcGeom::negate_;
-
 #ifndef IFOPSH_SIMPLE_KERNEL
 	class IFC_GEOMLIBRARY_API NumberEpeck : public OpaqueNumber {
 	private:
-		CGAL::Epeck::FT value_;
+		struct Model : OpaqueNumber::NumberConcept {
+			CGAL::Epeck::FT value;
 
-		template <CGAL::Epeck::FT(*Fn)(CGAL::Epeck::FT, CGAL::Epeck::FT)>
-		OpaqueNumber* binary_op(OpaqueNumber* other) const {
-			auto nnd = dynamic_cast<NumberEpeck*>(other);
-			if (nnd) {
-				return new NumberEpeck(Fn(value_, nnd->value_));
-			} else {
-				return nullptr;
+			Model(const CGAL::Epeck::FT& v)
+				: value(v) {}
+
+			static const Model& as_same(const NumberConcept& other) {
+				auto same = dynamic_cast<const Model*>(&other);
+				if (same == nullptr) {
+					throw std::runtime_error("Incompatible opaque number types");
+				}
+				return *same;
 			}
-		}
 
-		template <bool(*Fn)(CGAL::Epeck::FT, CGAL::Epeck::FT)>
-		bool binary_op_bool(OpaqueNumber* other) const {
-			auto nnd = dynamic_cast<NumberEpeck*>(other);
-			if (nnd) {
-				return Fn(value_, nnd->value_);
-			} else {
-				return false;
+			virtual double to_double() const {
+				return CGAL::to_double(value);
 			}
-		}
 
-		template <CGAL::Epeck::FT(*Fn)(CGAL::Epeck::FT)>
-		OpaqueNumber* unary_op() const {
-			return new NumberEpeck(Fn(value_));
-		}
+			virtual std::string to_string() const {
+				std::stringstream ss;
+				ss << value.exact();
+				return ss.str();
+			}
+
+			virtual std::shared_ptr<const NumberConcept> add(const NumberConcept& other) const {
+				return std::make_shared<Model>(value + as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> subtract(const NumberConcept& other) const {
+				return std::make_shared<Model>(value - as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> multiply(const NumberConcept& other) const {
+				return std::make_shared<Model>(value * as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> divide(const NumberConcept& other) const {
+				return std::make_shared<Model>(value / as_same(other).value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> negate() const {
+				return std::make_shared<Model>(-value);
+			}
+
+			virtual std::shared_ptr<const NumberConcept> from_double(double v) const {
+				return std::make_shared<Model>(CGAL::Epeck::FT(v));
+			}
+
+			virtual bool equals(const NumberConcept& other) const {
+				return value == as_same(other).value;
+			}
+
+			virtual bool less_than(const NumberConcept& other) const {
+				return value < as_same(other).value;
+			}
+
+			virtual const std::type_info& type() const {
+				return typeid(CGAL::Epeck::FT);
+			}
+
+			virtual const void* value_ptr() const {
+				return &value;
+			}
+		};
+
 	public:
 		NumberEpeck(const CGAL::Epeck::FT& v)
-			: value_(v) {}
-
-		virtual ~NumberEpeck() { }
-
-		virtual double to_double() const {
-			return CGAL::to_double(value_);
-		}
-
-		virtual std::string to_string() const {
-			std::stringstream ss;
-			ss << value_.exact();
-			return ss.str();
-		}
+			: OpaqueNumber(std::make_shared<Model>(v)) {}
 
 		const CGAL::Epeck::FT& value() const {
-			return value_;
-		}
-
-		virtual OpaqueNumber* operator+(OpaqueNumber* other) const {
-			return binary_op<add_<CGAL::Epeck::FT>>(other);
-		}
-		virtual OpaqueNumber* operator-(OpaqueNumber* other) const {
-			return binary_op<subtract_<CGAL::Epeck::FT>>(other);
-		}
-		virtual OpaqueNumber* operator*(OpaqueNumber* other) const {
-			return binary_op<multiply_<CGAL::Epeck::FT>>(other);
-		}
-		virtual OpaqueNumber* operator/(OpaqueNumber* other) const {
-			return binary_op<divide_<CGAL::Epeck::FT>>(other);
-		}
-		virtual bool operator==(OpaqueNumber* other) const {
-			return binary_op_bool<equals_<CGAL::Epeck::FT>>(other);
-		}
-		virtual bool operator<(OpaqueNumber* other) const {
-			return binary_op_bool<less_than_<CGAL::Epeck::FT>>(other);
-		}
-		virtual OpaqueNumber* operator-() const {
-			return unary_op<negate_<CGAL::Epeck::FT>>();
-		}
-		virtual OpaqueNumber* clone() const {
-			return new NumberEpeck(value_);
+			return value_as<CGAL::Epeck::FT>();
 		}
 	};
 #endif
@@ -253,9 +247,9 @@ namespace ifcopenshell { namespace geometry {
 		// @todo this must be something with a virtual dtor so that we can delete it.
 		virtual std::pair<OpaqueCoordinate<3>, OpaqueCoordinate<3>> bounding_box() const;
 
-		virtual OpaqueNumber* length();
-		virtual OpaqueNumber* area();
-		virtual OpaqueNumber* volume();
+		virtual OpaqueNumber length();
+		virtual OpaqueNumber area();
+		virtual OpaqueNumber volume();
 
 		virtual OpaqueCoordinate<3> position();
 		virtual OpaqueCoordinate<3> axis();
@@ -322,9 +316,9 @@ namespace ifcopenshell { namespace geometry {
 		virtual std::pair<OpaqueCoordinate<3>, OpaqueCoordinate<3>> bounding_box() const;
 		virtual void set_box(void* b);
 
-		virtual OpaqueNumber* length();
-		virtual OpaqueNumber* area();
-		virtual OpaqueNumber* volume();
+		virtual OpaqueNumber length();
+		virtual OpaqueNumber area();
+		virtual OpaqueNumber volume();
 
 		virtual OpaqueCoordinate<3> position();
 		virtual OpaqueCoordinate<3> axis();
diff --git a/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.cpp b/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.cpp
index 36e423730e..37f38c303e 100644
--- a/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.cpp
+++ b/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.cpp
@@ -385,28 +385,28 @@ int ifcopenshell::geometry::OpenCascadeShape::num_faces() const
 	return IfcGeom::util::count(shape_, TopAbs_FACE);
 }
 
-OpaqueNumber* ifcopenshell::geometry::OpenCascadeShape::OpenCascadeShape::length()
+OpaqueNumber ifcopenshell::geometry::OpenCascadeShape::OpenCascadeShape::length()
 {
 	GProp_GProps prop;
 	BRepGProp::LinearProperties(shape_, prop);
 	double l = prop.Mass();
-	return new NumberNativeDouble(l);
+	return NumberNativeDouble(l);
 }
 
-OpaqueNumber* ifcopenshell::geometry::OpenCascadeShape::area()
+OpaqueNumber ifcopenshell::geometry::OpenCascadeShape::area()
 {
 	GProp_GProps prop;
 	BRepGProp::SurfaceProperties(shape_, prop);
 	double l = prop.Mass();
-	return new NumberNativeDouble(l);
+	return NumberNativeDouble(l);
 }
 
-OpaqueNumber* ifcopenshell::geometry::OpenCascadeShape::volume()
+OpaqueNumber ifcopenshell::geometry::OpenCascadeShape::volume()
 {
 	GProp_GProps prop;
 	BRepGProp::VolumeProperties(shape_, prop);
 	double l = prop.Mass();
-	return new NumberNativeDouble(l);
+	return NumberNativeDouble(l);
 }
 
 #include <Geom_Plane.hxx>
@@ -419,9 +419,9 @@ OpaqueCoordinate<3> ifcopenshell::geometry::OpenCascadeShape::position()
 		if (plane) {
 			auto loc = plane->Location();
 			return OpaqueCoordinate<3>(
-				new NumberNativeDouble(loc.X()),
-				new NumberNativeDouble(loc.Y()),
-				new NumberNativeDouble(loc.Z())
+				NumberNativeDouble(loc.X()),
+				NumberNativeDouble(loc.Y()),
+				NumberNativeDouble(loc.Z())
 			);
 		}
 	}
@@ -436,9 +436,9 @@ OpaqueCoordinate<3> ifcopenshell::geometry::OpenCascadeShape::axis()
 		if (plane) {
 			auto dir = plane->Axis().Direction();
 			return OpaqueCoordinate<3>(
-				new NumberNativeDouble(dir.X()),
-				new NumberNativeDouble(dir.Y()),
-				new NumberNativeDouble(dir.Z())
+				NumberNativeDouble(dir.X()),
+				NumberNativeDouble(dir.Y()),
+				NumberNativeDouble(dir.Z())
 			);
 		}
 	}
@@ -454,10 +454,10 @@ OpaqueCoordinate<4> ifcopenshell::geometry::OpenCascadeShape::plane_equation()
 			double a, b, c, d;
 			plane->Pln().Coefficients(a, b, c, d);
 			return OpaqueCoordinate<4>(
-				new NumberNativeDouble(a),
-				new NumberNativeDouble(b),
-				new NumberNativeDouble(c),
-				new NumberNativeDouble(d)
+				NumberNativeDouble(a),
+				NumberNativeDouble(b),
+				NumberNativeDouble(c),
+				NumberNativeDouble(d)
 			);
 		}
 	}
diff --git a/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.h b/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.h
index 643c797905..70b612feba 100644
--- a/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.h
+++ b/src/ifcgeom/kernels/opencascade/OpenCascadeConversionResult.h
@@ -78,9 +78,9 @@ namespace ifcopenshell {
 			// @todo this must be something with a virtual dtor so that we can delete it.
 			virtual std::pair<OpaqueCoordinate<3>, OpaqueCoordinate<3>> bounding_box() const;
 
-			virtual OpaqueNumber* length();
-			virtual OpaqueNumber* area();
-			virtual OpaqueNumber* volume();
+			virtual OpaqueNumber length();
+			virtual OpaqueNumber area();
+			virtual OpaqueNumber volume();
 
 			virtual OpaqueCoordinate<3> position();
 			virtual OpaqueCoordinate<3> axis();
diff --git a/src/ifcwrap/IfcGeomWrapper.i b/src/ifcwrap/IfcGeomWrapper.i
index 10d9083403..20e687e04e 100644
--- a/src/ifcwrap/IfcGeomWrapper.i
+++ b/src/ifcwrap/IfcGeomWrapper.i
@@ -83,16 +83,9 @@
 %newobject IfcGeom::ConversionResultShape::moved;
 %newobject IfcGeom::ConversionResultShape::wrap_in_compound;
 
-%newobject IfcGeom::ConversionResultShape::area;
-%newobject IfcGeom::ConversionResultShape::volume;
-%newobject IfcGeom::ConversionResultShape::length;
 
 %newobject nary_union;
 
-%newobject IfcGeom::OpaqueNumber::operator+;
-%newobject IfcGeom::OpaqueNumber::operator-;
-%newobject IfcGeom::OpaqueNumber::operator*;
-%newobject IfcGeom::OpaqueNumber::operator/;
 
 %inline %{
 template <typename T>
@@ -1180,17 +1173,15 @@ ifcopenshell::geometry::taxonomy::item::ptr try_upcast(PyObject* obj0, swig_type
 %template(OpaqueCoordinate_3) IfcGeom::OpaqueCoordinate<3>;
 %template(OpaqueCoordinate_4) IfcGeom::OpaqueCoordinate<4>;
 
-%newobject create_epeck;
-
 %inline %{
-	IfcGeom::OpaqueNumber* create_epeck(int i) {
-		return new ifcopenshell::geometry::NumberEpeck(i);
+	IfcGeom::OpaqueNumber create_epeck(int i) {
+		return ifcopenshell::geometry::NumberEpeck(i);
 	}
-	IfcGeom::OpaqueNumber* create_epeck(double d) {
-		return new ifcopenshell::geometry::NumberEpeck(d);
+	IfcGeom::OpaqueNumber create_epeck(double d) {
+		return ifcopenshell::geometry::NumberEpeck(d);
 	}
-	IfcGeom::OpaqueNumber* create_epeck(const std::string& s) {
-		return new ifcopenshell::geometry::NumberEpeck(typename CGAL::Epeck::FT::ET(s));
+	IfcGeom::OpaqueNumber create_epeck(const std::string& s) {
+		return ifcopenshell::geometry::NumberEpeck(typename CGAL::Epeck::FT::ET(s));
 	}
 %}