diff --git a/conandata.yml b/conandata.yml
index 0644c1a..1ac66bd 100644
--- a/conandata.yml
+++ b/conandata.yml
@@ -1 +1 @@
-version: "5.11.0-alpha.0"
+version: "5.12.0"
diff --git a/include/Savitar/MeshData.h b/include/Savitar/MeshData.h
index 5c3e806..744ac62 100644
--- a/include/Savitar/MeshData.h
+++ b/include/Savitar/MeshData.h
@@ -35,7 +35,7 @@ class MeshData
     /**
      * Serialise the meshData to xml_node
      */
-    void toXmlNode(pugi::xml_node& xml_node);
+    void toXmlNode(pugi::xml_node& xml_node) const;
 
     /**
      * Return the vertices as flattend bytes.
@@ -49,7 +49,7 @@ class MeshData
      *
      * If there for example is a single face, it will return a byte array containing 3 ints (so 3 * 4 bytes)
      */
-    [[nodiscard]] bytearray getFacesAsBytes();
+    [[nodiscard]] bytearray getFacesAsBytes() const;
 
     /**
      * Instead of getting all unique vertices, this function returns a bytearray with 3 vertices per face.
@@ -93,7 +93,11 @@ class MeshData
      */
     void setFacesFromBytes(const bytearray& data);
 
-    [[nodiscard]] std::vector<Vertex> getVertices();
+    [[nodiscard]] const std::vector<Vertex>& getVertices() const;
+
+    [[nodiscard]] const std::vector<Face>& getFaces() const;
+
+    [[nodiscard]] int getUVGroupId() const;
 
     /**
      * Reset the data of the MeshData object.
@@ -116,4 +120,4 @@ class MeshData
 };
 } // namespace Savitar
 
-#endif
\ No newline at end of file
+#endif
diff --git a/include/Savitar/Scene.h b/include/Savitar/Scene.h
index 651e3aa..b54a81f 100644
--- a/include/Savitar/Scene.h
+++ b/include/Savitar/Scene.h
@@ -28,7 +28,7 @@ class Scene
      * Get the scene nodes in this scene.
      * \return The scene nodes that are in the scene.
      */
-    [[nodiscard]] std::vector<SceneNode*> getSceneNodes();
+    [[nodiscard]] const std::vector<SceneNode*>& getSceneNodes() const;
 
     [[nodiscard]] std::vector<SceneNode*> getAllSceneNodes() const;
 
@@ -46,7 +46,7 @@ class Scene
     /**
      * Serialise the scene to model_node
      */
-    void toXmlNode(pugi::xml_node& model_node);
+    void toXmlNode(pugi::xml_node& model_node) const;
 
     /**
      * Store a metadata entry as metadata.
@@ -84,7 +84,7 @@ class Scene
      * Get the unit (milimeter, inch, etc) of the scene.
      * This is in milimeter by default.
      */
-    [[nodiscard]] std::string getUnit();
+    [[nodiscard]] const std::string& getUnit() const;
 
     void setUnit(std::string unit);
 
@@ -116,4 +116,4 @@ class Scene
     SceneNode* createSceneNodeFromObject(pugi::xml_node root_node, pugi::xml_node object_node);
 };
 } // namespace Savitar
-#endif
\ No newline at end of file
+#endif
diff --git a/include/Savitar/SceneNode.h b/include/Savitar/SceneNode.h
index 6821683..1339902 100644
--- a/include/Savitar/SceneNode.h
+++ b/include/Savitar/SceneNode.h
@@ -21,14 +21,14 @@ class SceneNode
     SceneNode() = default;
     virtual ~SceneNode() = default;
 
-    [[nodiscard]] std::string getTransformation();
-    void setTransformation(std::string);
+    [[nodiscard]] const std::string& getTransformation() const;
+    void setTransformation(const std::string& transformation);
 
-    [[nodiscard]] std::vector<SceneNode*> getChildren();
-    [[nodiscard]] std::vector<SceneNode*> getAllChildren();
+    [[nodiscard]] const std::vector<SceneNode*>& getChildren() const;
+    [[nodiscard]] std::vector<SceneNode*> getAllChildren() const;
     bool addChild(SceneNode* node);
 
-    MeshData& getMeshData();
+    [[nodiscard]] const MeshData& getMeshData() const;
     void setMeshData(const MeshData& mesh_data);
 
     /**
@@ -51,7 +51,7 @@ class SceneNode
     /**
      * Get the (non-unique) display name of the node.
      */
-    [[nodiscard]] std::string getName();
+    [[nodiscard]] const std::string& getName() const;
 
     [[maybe_unused]] void setName(std::string name);
 
diff --git a/include/Savitar/TextureData.h b/include/Savitar/TextureData.h
index 9524406..088866e 100644
--- a/include/Savitar/TextureData.h
+++ b/include/Savitar/TextureData.h
@@ -31,7 +31,7 @@ class TextureData
 
     void fillByXMLNode(pugi::xml_node xml_node);
 
-    void toXmlNode(pugi::xml_node& resources_node);
+    void toXmlNode(pugi::xml_node& resources_node) const;
 
     [[nodiscard]] std::string getTexturePath(const int texture_id) const;
 
@@ -61,4 +61,4 @@ class TextureData
 };
 } // namespace Savitar
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/MeshData.cpp b/src/MeshData.cpp
index 4206545..25a0cc0 100644
--- a/src/MeshData.cpp
+++ b/src/MeshData.cpp
@@ -204,7 +204,7 @@ std::string MeshData::getTexturePath(const Scene* scene) const
     return scene->getTexturePathFromGroupId(uv_group_id_);
 }
 
-bytearray MeshData::getFacesAsBytes()
+bytearray MeshData::getFacesAsBytes() const
 {
     bytearray face_data;
 
@@ -220,7 +220,7 @@ bytearray MeshData::getFacesAsBytes()
     return face_data;
 }
 
-void MeshData::toXmlNode(pugi::xml_node& node)
+void MeshData::toXmlNode(pugi::xml_node& node) const
 {
     pugi::xml_node vertices_node = node.append_child("vertices");
     for (auto& vertice : vertices_)
@@ -288,13 +288,23 @@ void MeshData::setFacesFromBytes(const bytearray& data)
     }
 }
 
-std::vector<Vertex> MeshData::getVertices()
+const std::vector<Vertex>& MeshData::getVertices() const
 {
     return vertices_;
 }
 
+const std::vector<Face>& MeshData::getFaces() const
+{
+    return faces_;
+}
+
+int MeshData::getUVGroupId() const
+{
+    return uv_group_id_;
+}
+
 template<typename T>
 void MeshData::exportToByteArray(bytearray& data, const T value)
 {
     data.insert(data.end(), reinterpret_cast<const uint8_t*>(&value), reinterpret_cast<const uint8_t*>(&value) + sizeof(T));
-}
\ No newline at end of file
+}
diff --git a/src/Scene.cpp b/src/Scene.cpp
index 6a69f3d..f351a8d 100644
--- a/src/Scene.cpp
+++ b/src/Scene.cpp
@@ -10,7 +10,7 @@
 
 using namespace Savitar;
 
-std::vector<SceneNode*> Scene::getSceneNodes()
+const std::vector<SceneNode*>& Scene::getSceneNodes() const
 {
     return scene_nodes_;
 }
@@ -87,7 +87,7 @@ void Scene::fillByXMLNode(pugi::xml_node xml_node)
     }
 }
 
-void Scene::toXmlNode(pugi::xml_node& model_node)
+void Scene::toXmlNode(pugi::xml_node& model_node) const
 {
     pugi::xml_node resources_node = model_node.append_child("resources");
     pugi::xml_node build_node = model_node.append_child("build");
@@ -286,7 +286,7 @@ void Scene::setMetaDataEntry(const std::string& key, const std::string& value, c
     metadata_.emplace(key, MetadataEntry(value, type, preserve));
 }
 
-std::string Scene::getUnit()
+const std::string& Scene::getUnit() const
 {
     return unit_;
 }
diff --git a/src/SceneNode.cpp b/src/SceneNode.cpp
index ba86548..c0a9d50 100644
--- a/src/SceneNode.cpp
+++ b/src/SceneNode.cpp
@@ -8,12 +8,12 @@
 
 using namespace Savitar;
 
-std::string SceneNode::getTransformation()
+const std::string& SceneNode::getTransformation() const
 {
     return transformation_;
 }
 
-void SceneNode::setTransformation(std::string transformation)
+void SceneNode::setTransformation(const std::string& transformation)
 {
     transformation_ = transformation;
 }
@@ -28,7 +28,7 @@ std::string SceneNode::getComponentPath() const
     return component_path_;
 }
 
-std::vector<SceneNode*> SceneNode::getChildren()
+const std::vector<SceneNode*>& SceneNode::getChildren() const
 {
     return children_;
 }
@@ -52,7 +52,7 @@ bool SceneNode::addChild(SceneNode* node)
     return true;
 }
 
-MeshData& SceneNode::getMeshData()
+const MeshData& SceneNode::getMeshData() const
 {
     return mesh_data_;
 }
@@ -181,7 +181,7 @@ void SceneNode::setId(const int id)
     id_ = id;
 }
 
-std::string SceneNode::getName()
+const std::string& SceneNode::getName() const
 {
     return name_;
 }
@@ -212,7 +212,7 @@ void SceneNode::removeSetting(std::string key)
 }
 
 
-std::vector<SceneNode*> SceneNode::getAllChildren()
+std::vector<SceneNode*> SceneNode::getAllChildren() const
 {
     std::vector<SceneNode*> all_children;
 
diff --git a/src/TextureData.cpp b/src/TextureData.cpp
index e4b25bf..68bac07 100644
--- a/src/TextureData.cpp
+++ b/src/TextureData.cpp
@@ -45,7 +45,7 @@ void TextureData::fillByXMLNode(pugi::xml_node xml_node)
     }
 }
 
-void TextureData::toXmlNode(pugi::xml_node& resources_node)
+void TextureData::toXmlNode(pugi::xml_node& resources_node) const
 {
     // Handle textures paths
     for (const auto& texture_path : textures_paths_)
diff --git a/tests/ThreeMFParserTest.cpp b/tests/ThreeMFParserTest.cpp
index 0cdf25d..7645889 100644
--- a/tests/ThreeMFParserTest.cpp
+++ b/tests/ThreeMFParserTest.cpp
@@ -60,10 +60,10 @@ TEST_F(ThreeMFParserTest, parse)
     std::array<size_t, 4> expected_tris = { 144UL, 144UL, 0UL, 0UL };
     std::array<size_t, 4> expected_child = { 0UL, 0UL, 1UL, 1UL };
     int i = -1;
-    for (SceneNode* node : nodes)
+    for (const SceneNode* node : nodes)
     {
         ++i;
-        MeshData& data = node->getMeshData();
+        const MeshData& data = node->getMeshData();
 
         const std::vector<Vertex>& verts = data.getVertices();
         EXPECT_EQ(verts.size(), expected_verts[i]);
@@ -71,13 +71,13 @@ TEST_F(ThreeMFParserTest, parse)
         const bytearray& tris = data.getFacesAsBytes();
         EXPECT_EQ(tris.size(), expected_tris[i]);
 
-        const std::vector<SceneNode*>& children = node->getAllChildren();
+        const std::vector<SceneNode*> children = node->getAllChildren();
         ASSERT_EQ(children.size(), expected_child[i]);
-        for (SceneNode* child : children)
+        for (const SceneNode* child : children)
         {
-            data = child->getMeshData();
-            EXPECT_FALSE(data.getVertices().empty());
-            EXPECT_FALSE(data.getFacesAsBytes().empty());
+            const MeshData& child_data = child->getMeshData();
+            EXPECT_FALSE(child_data.getVertices().empty());
+            EXPECT_FALSE(child_data.getFacesAsBytes().empty());
         }
     }
     // NOTE: To/from for content of vertices/triangles is tested in MeshDataTest.