diff --git a/res/generators/default.files/tree0.vox b/res/generators/default.files/tree0.vox
new file mode 100644
index 00000000..3bcff693
Binary files /dev/null and b/res/generators/default.files/tree0.vox differ
diff --git a/res/scripts/world.lua b/res/scripts/world.lua
index 964100e7..d2726162 100644
--- a/res/scripts/world.lua
+++ b/res/scripts/world.lua
@@ -1,3 +1,4 @@
 -- use for engine development tests
 -- must be empty in release
 -- must not be modified by content-packs
+print(generation.load_structure("core:generators/default.files/tree0.vox"))
diff --git a/src/logic/scripting/lua/libfile.cpp b/src/logic/scripting/lua/libfile.cpp
index 5da4358d..30c0e204 100644
--- a/src/logic/scripting/lua/libfile.cpp
+++ b/src/logic/scripting/lua/libfile.cpp
@@ -158,7 +158,7 @@ static int l_file_write_bytes(lua::State* L) {
 
     fs::path path = resolve_path(lua::require_string(L, pathIndex));
 
-    if (auto bytearray = lua::touserdata<lua::Bytearray>(L, -1)) {
+    if (auto bytearray = lua::touserdata<lua::LuaBytearray>(L, -1)) {
         auto& bytes = bytearray->data();
         return lua::pushboolean(
             L, files::write_bytes(path, bytes.data(), bytes.size())
diff --git a/src/logic/scripting/lua/libgeneration.cpp b/src/logic/scripting/lua/libgeneration.cpp
index 956c28e5..c38716e9 100644
--- a/src/logic/scripting/lua/libgeneration.cpp
+++ b/src/logic/scripting/lua/libgeneration.cpp
@@ -5,6 +5,8 @@
 #include "coders/binary_json.hpp"
 #include "world/Level.hpp"
 #include "world/generator/VoxelStructure.hpp"
+#include "engine.hpp"
+#include "lua_custom_types.hpp"
 
 using namespace scripting;
 
@@ -25,6 +27,21 @@ static int l_save_structure(lua::State* L) {
     return 0;
 }
 
+static int l_load_structure(lua::State* L) {
+    auto paths = engine->getPaths();
+    auto filename = lua::require_string(L, 1);
+    auto path = paths->resolve(filename);
+    if (!std::filesystem::exists(path)) {
+        throw std::runtime_error("file "+path.u8string()+" does not exist");
+    }
+    auto map = files::read_binary_json(path);
+
+    auto structure = std::make_shared<VoxelStructure>();
+    structure->deserialize(map);
+    return lua::newuserdata<lua::LuaVoxelStructure>(L, std::move(structure));
+}
+
 const luaL_Reg generationlib[] = {
     {"save_structure", lua::wrap<l_save_structure>},
+    {"load_structure", lua::wrap<l_load_structure>},
     {NULL, NULL}};
diff --git a/src/logic/scripting/lua/lua_custom_types.hpp b/src/logic/scripting/lua/lua_custom_types.hpp
index d6a7ba0b..67faeef4 100644
--- a/src/logic/scripting/lua/lua_custom_types.hpp
+++ b/src/logic/scripting/lua/lua_custom_types.hpp
@@ -4,9 +4,10 @@
 #include <vector>
 
 #include "lua_commons.hpp"
-#include "maths/Heightmap.hpp"
 
 struct fnl_state;
+class Heightmap;
+class VoxelStructure;
 
 namespace lua {
     class Userdata {
@@ -15,12 +16,12 @@ namespace lua {
         virtual const std::string& getTypeName() const = 0;
     };
 
-    class Bytearray : public Userdata {
+    class LuaBytearray : public Userdata {
         std::vector<ubyte> buffer;
     public:
-        Bytearray(size_t capacity);
-        Bytearray(std::vector<ubyte> buffer);
-        virtual ~Bytearray();
+        LuaBytearray(size_t capacity);
+        LuaBytearray(std::vector<ubyte> buffer);
+        virtual ~LuaBytearray();
 
         const std::string& getTypeName() const override {
             return TYPENAME;
@@ -32,6 +33,7 @@ namespace lua {
         static int createMetatable(lua::State*);
         inline static std::string TYPENAME = "Bytearray";
     };
+    static_assert(!std::is_abstract<LuaBytearray>());
 
     class LuaHeightmap : public Userdata {
         std::shared_ptr<Heightmap> map;
@@ -41,21 +43,13 @@ namespace lua {
 
         virtual ~LuaHeightmap();
 
-        uint getWidth() const {
-            return map->getWidth();
-        }
+        uint getWidth() const;
 
-        uint getHeight() const {
-            return map->getHeight();
-        }
+        uint getHeight() const;
 
-        float* getValues() {
-            return map->getValues();
-        }
+        float* getValues();
 
-        const float* getValues() const {
-            return map->getValues();
-        }
+        const float* getValues() const;
 
         const std::string& getTypeName() const override {
             return TYPENAME;
@@ -74,4 +68,25 @@ namespace lua {
         static int createMetatable(lua::State*);
         inline static std::string TYPENAME = "Heightmap";
     };
+    static_assert(!std::is_abstract<LuaHeightmap>());
+
+    class LuaVoxelStructure : public Userdata {
+        std::shared_ptr<VoxelStructure> structure;
+    public:
+        LuaVoxelStructure(std::shared_ptr<VoxelStructure> structure);
+
+        virtual ~LuaVoxelStructure();
+
+        std::shared_ptr<VoxelStructure> getStructure() const {
+            return structure;
+        }
+
+        const std::string& getTypeName() const override {
+            return TYPENAME;
+        }
+
+        static int createMetatable(lua::State*);
+        inline static std::string TYPENAME = "VoxelStructure";
+    };
+    static_assert(!std::is_abstract<LuaVoxelStructure>());
 }
diff --git a/src/logic/scripting/lua/lua_engine.cpp b/src/logic/scripting/lua/lua_engine.cpp
index 879ec4c6..6ae427e3 100644
--- a/src/logic/scripting/lua/lua_engine.cpp
+++ b/src/logic/scripting/lua/lua_engine.cpp
@@ -96,8 +96,9 @@ void lua::initialize() {
 
     initialize_libs_extends(L);
 
-    newusertype<Bytearray, Bytearray::createMetatable>(L, "Bytearray");
-    newusertype<LuaHeightmap, LuaHeightmap::createMetatable>(L, "Heightmap");
+    newusertype<LuaBytearray>(L);
+    newusertype<LuaHeightmap>(L);
+    newusertype<LuaVoxelStructure>(L);
 }
 
 void lua::finalize() {
diff --git a/src/logic/scripting/lua/lua_util.hpp b/src/logic/scripting/lua/lua_util.hpp
index fc202555..f365cdba 100644
--- a/src/logic/scripting/lua/lua_util.hpp
+++ b/src/logic/scripting/lua/lua_util.hpp
@@ -248,10 +248,12 @@ namespace lua {
         return 1;
     }
 
-    template <class T, lua_CFunction func>
-    inline void newusertype(lua::State* L, const std::string& name) {
+    template <class T>
+    inline std::enable_if_t<std::is_base_of_v<Userdata, T>> 
+    newusertype(lua::State* L) {
+        const std::string& name = T::TYPENAME;
         usertypeNames[typeid(T)] = name;
-        func(L);
+        T::createMetatable(L);
 
         pushcfunction(L, userdata_destructor);
         setfield(L, "__gc");
diff --git a/src/logic/scripting/lua/lua_type_bytearray.cpp b/src/logic/scripting/lua/usertypes/lua_type_bytearray.cpp
similarity index 81%
rename from src/logic/scripting/lua/lua_type_bytearray.cpp
rename to src/logic/scripting/lua/usertypes/lua_type_bytearray.cpp
index cf41f318..7be3fc10 100644
--- a/src/logic/scripting/lua/lua_type_bytearray.cpp
+++ b/src/logic/scripting/lua/usertypes/lua_type_bytearray.cpp
@@ -1,23 +1,23 @@
-#include "lua_custom_types.hpp"
+#include "../lua_custom_types.hpp"
 
 #include <sstream>
 
-#include "lua_util.hpp"
+#include "../lua_util.hpp"
 
 using namespace lua;
 
-Bytearray::Bytearray(size_t capacity) : buffer(capacity) {
+LuaBytearray::LuaBytearray(size_t capacity) : buffer(capacity) {
     buffer.resize(capacity);
 }
 
-Bytearray::Bytearray(std::vector<ubyte> buffer) : buffer(std::move(buffer)) {
+LuaBytearray::LuaBytearray(std::vector<ubyte> buffer) : buffer(std::move(buffer)) {
 }
 
-Bytearray::~Bytearray() {
+LuaBytearray::~LuaBytearray() {
 }
 
 static int l_append(lua::State* L) {
-    if (auto buffer = touserdata<Bytearray>(L, 1)) {
+    if (auto buffer = touserdata<LuaBytearray>(L, 1)) {
         auto value = tointeger(L, 2);
         buffer->data().push_back(static_cast<ubyte>(value));
     }
@@ -25,7 +25,7 @@ static int l_append(lua::State* L) {
 }
 
 static int l_insert(lua::State* L) {
-    auto buffer = touserdata<Bytearray>(L, 1);
+    auto buffer = touserdata<LuaBytearray>(L, 1);
     if (buffer == nullptr) {
         return 0;
     }
@@ -40,7 +40,7 @@ static int l_insert(lua::State* L) {
 }
 
 static int l_remove(lua::State* L) {
-    auto buffer = touserdata<Bytearray>(L, 1);
+    auto buffer = touserdata<LuaBytearray>(L, 1);
     if (buffer == nullptr) {
         return 0;
     }
@@ -69,17 +69,17 @@ static int l_meta_meta_call(lua::State* L) {
             buffer[i] = static_cast<ubyte>(tointeger(L, -1));
             pop(L);
         }
-        return newuserdata<Bytearray>(L, std::move(buffer));
+        return newuserdata<LuaBytearray>(L, std::move(buffer));
     }
     auto size = tointeger(L, 2);
     if (size < 0) {
         throw std::runtime_error("size can not be less than 0");
     }
-    return newuserdata<Bytearray>(L, static_cast<size_t>(size));
+    return newuserdata<LuaBytearray>(L, static_cast<size_t>(size));
 }
 
 static int l_meta_index(lua::State* L) {
-    auto buffer = touserdata<Bytearray>(L, 1);
+    auto buffer = touserdata<LuaBytearray>(L, 1);
     if (buffer == nullptr) {
         return 0;
     }
@@ -98,7 +98,7 @@ static int l_meta_index(lua::State* L) {
 }
 
 static int l_meta_newindex(lua::State* L) {
-    auto buffer = touserdata<Bytearray>(L, 1);
+    auto buffer = touserdata<LuaBytearray>(L, 1);
     if (buffer == nullptr) {
         return 0;
     }
@@ -116,14 +116,14 @@ static int l_meta_newindex(lua::State* L) {
 }
 
 static int l_meta_len(lua::State* L) {
-    if (auto buffer = touserdata<Bytearray>(L, 1)) {
+    if (auto buffer = touserdata<LuaBytearray>(L, 1)) {
         return pushinteger(L, buffer->data().size());
     }
     return 0;
 }
 
 static int l_meta_tostring(lua::State* L) {
-    auto buffer = touserdata<Bytearray>(L, 1);
+    auto buffer = touserdata<LuaBytearray>(L, 1);
     if (buffer == nullptr) {
         return 0;
     }
@@ -147,8 +147,8 @@ static int l_meta_tostring(lua::State* L) {
 }
 
 static int l_meta_add(lua::State* L) {
-    auto bufferA = touserdata<Bytearray>(L, 1);
-    auto bufferB = touserdata<Bytearray>(L, 2);
+    auto bufferA = touserdata<LuaBytearray>(L, 1);
+    auto bufferB = touserdata<LuaBytearray>(L, 2);
     if (bufferA == nullptr || bufferB == nullptr) {
         return 0;
     }
@@ -159,10 +159,10 @@ static int l_meta_add(lua::State* L) {
     ab.reserve(dataA.size() + dataB.size());
     ab.insert(ab.end(), dataA.begin(), dataA.end());
     ab.insert(ab.end(), dataB.begin(), dataB.end());
-    return newuserdata<Bytearray>(L, std::move(ab));
+    return newuserdata<LuaBytearray>(L, std::move(ab));
 }
 
-int Bytearray::createMetatable(lua::State* L) {
+int LuaBytearray::createMetatable(lua::State* L) {
     createtable(L, 0, 6);
     pushcfunction(L, lua::wrap<l_meta_index>);
     setfield(L, "__index");
diff --git a/src/logic/scripting/lua/lua_type_heightmap.cpp b/src/logic/scripting/lua/usertypes/lua_type_heightmap.cpp
similarity index 95%
rename from src/logic/scripting/lua/lua_type_heightmap.cpp
rename to src/logic/scripting/lua/usertypes/lua_type_heightmap.cpp
index f467dc35..fc766c53 100644
--- a/src/logic/scripting/lua/lua_type_heightmap.cpp
+++ b/src/logic/scripting/lua/usertypes/lua_type_heightmap.cpp
@@ -1,4 +1,4 @@
-#include "lua_custom_types.hpp"
+#include "../lua_custom_types.hpp"
 
 #include <cstring>
 #include <sstream>
@@ -11,7 +11,8 @@
 #include "coders/png.hpp"
 #include "files/util.hpp"
 #include "graphics/core/ImageData.hpp"
-#include "lua_util.hpp"
+#include "maths/Heightmap.hpp"
+#include "../lua_util.hpp"
 
 using namespace lua;
 
@@ -27,6 +28,22 @@ void LuaHeightmap::setSeed(int64_t seed) {
     noise->seed = seed;
 }
 
+uint LuaHeightmap::getWidth() const {
+    return map->getWidth();
+}
+
+uint LuaHeightmap::getHeight() const {
+    return map->getHeight();
+}
+
+float* LuaHeightmap::getValues() {
+    return map->getValues();
+}
+
+const float* LuaHeightmap::getValues() const {
+    return map->getValues();
+}
+
 static int l_dump(lua::State* L) {
     if (auto heightmap = touserdata<LuaHeightmap>(L, 1)) {
         auto filename = require_string(L, 2);
diff --git a/src/logic/scripting/lua/usertypes/lua_type_voxelstructure.cpp b/src/logic/scripting/lua/usertypes/lua_type_voxelstructure.cpp
new file mode 100644
index 00000000..b35ed517
--- /dev/null
+++ b/src/logic/scripting/lua/usertypes/lua_type_voxelstructure.cpp
@@ -0,0 +1,26 @@
+#include "../lua_custom_types.hpp"
+
+#include "../lua_util.hpp"
+
+#include "world/generator/VoxelStructure.hpp"
+#include "util/stringutil.hpp"
+
+using namespace lua;
+
+LuaVoxelStructure::LuaVoxelStructure(std::shared_ptr<VoxelStructure> structure)
+    : structure(std::move(structure)) {}
+
+LuaVoxelStructure::~LuaVoxelStructure() {
+}
+
+static int l_meta_tostring(lua::State* L) {
+    return pushstring(L, "VoxelStructure(0x" + util::tohex(
+        reinterpret_cast<uint64_t>(topointer(L, 1)))+")");
+}
+
+int LuaVoxelStructure::createMetatable(lua::State* L) {
+    createtable(L, 0, 1);
+    pushcfunction(L, lua::wrap<l_meta_tostring>);
+    setfield(L, "__tostring");
+    return 1;
+}
diff --git a/src/maths/Heightmap.hpp b/src/maths/Heightmap.hpp
index 52a3d394..8e7e5594 100644
--- a/src/maths/Heightmap.hpp
+++ b/src/maths/Heightmap.hpp
@@ -4,6 +4,7 @@
 #include <string>
 
 #include "typedefs.hpp"
+#include "maths/Heightmap.hpp"
 
 enum class InterpolationType {
     NEAREST,
diff --git a/src/util/stringutil.cpp b/src/util/stringutil.cpp
index 4452301b..d1e5ef9f 100644
--- a/src/util/stringutil.cpp
+++ b/src/util/stringutil.cpp
@@ -312,13 +312,17 @@ std::string util::base64_encode(const ubyte* data, size_t size) {
     return ss.str();
 }
 
-std::string util::mangleid(uint64_t value) {
-    // todo: use base64
+std::string util::tohex(uint64_t value) {
     std::stringstream ss;
     ss << std::hex << value;
     return ss.str();
 }
 
+std::string util::mangleid(uint64_t value) {
+    // todo: use base64
+    return tohex(value);
+}
+
 util::Buffer<ubyte> util::base64_decode(const char* str, size_t size) {
     util::Buffer<ubyte> bytes((size / 4) * 3);
     ubyte* dst = bytes.data();
diff --git a/src/util/stringutil.hpp b/src/util/stringutil.hpp
index 21d58e5e..cb251e83 100644
--- a/src/util/stringutil.hpp
+++ b/src/util/stringutil.hpp
@@ -60,6 +60,8 @@ namespace util {
     util::Buffer<ubyte> base64_decode(const char* str, size_t size);
     util::Buffer<ubyte> base64_decode(const std::string& str);
 
+    std::string tohex(uint64_t value);
+
     std::string mangleid(uint64_t value);
 
     int replaceAll(
diff --git a/src/world/generator/VoxelStructure.cpp b/src/world/generator/VoxelStructure.cpp
index 1b7abe4d..b7595064 100644
--- a/src/world/generator/VoxelStructure.cpp
+++ b/src/world/generator/VoxelStructure.cpp
@@ -66,11 +66,23 @@ dv::value VoxelStructure::serialize() const {
 void VoxelStructure::deserialize(const dv::value& src) {
     size = glm::ivec3();
     dv::get_vec(src, "size", size);
-    voxels.resize(size.x*size.y*size.z);
+
+    auto volume = size.x*size.y*size.z;
+    voxels.resize(volume);
 
     const auto& voxelsArr = src["voxels"];
-    for (size_t i = 0; i < size.x*size.y*size.z; i++) {
+    for (size_t i = 0; i < volume; i++) {
         voxels[i].id = voxelsArr[i * 2].asInteger();
         voxels[i].state = int2blockstate(voxelsArr[i * 2 + 1].asInteger());
     }
 }
+
+void VoxelStructure::prepare(const Content& content) {
+    auto volume = size.x*size.y*size.z;
+    voxelsRuntime.resize(volume);
+    for (size_t i = 0; i < volume; i++) {
+        const auto& name = blockNames[voxels[i].id];
+        voxelsRuntime[i].id = content.blocks.require(name).rt.id;
+        voxelsRuntime[i].state = voxels[i].state;
+    }
+}
diff --git a/src/world/generator/VoxelStructure.hpp b/src/world/generator/VoxelStructure.hpp
index 68819653..444a1f1a 100644
--- a/src/world/generator/VoxelStructure.hpp
+++ b/src/world/generator/VoxelStructure.hpp
@@ -11,7 +11,7 @@ inline constexpr int STRUCTURE_FORMAT_VERSION = 1;
 class Level;
 class Content;
 
-struct VoxelStructure : public Serializable {
+class VoxelStructure : public Serializable {
     glm::ivec3 size;
 
     /// @brief Structure voxels indexed different to world content
@@ -19,6 +19,9 @@ struct VoxelStructure : public Serializable {
     /// @brief Block names are used for indexing
     std::vector<std::string> blockNames;
 
+    /// @brief Structure voxels built on prepare(...) call
+    std::vector<voxel> voxelsRuntime;
+public:
     VoxelStructure() : size() {}
 
     VoxelStructure(
@@ -33,6 +36,18 @@ struct VoxelStructure : public Serializable {
     dv::value serialize() const override;
     void deserialize(const dv::value& src) override;
 
+    /// @brief Build runtime voxel indices
+    /// @param content world content
+    void prepare(const Content& content);
+
     static std::unique_ptr<VoxelStructure> create(
         Level* level, const glm::ivec3& a, const glm::ivec3& b, bool entities);
+
+    const glm::ivec3& getSize() const {
+        return size;
+    }
+
+    const std::vector<voxel>& getRuntimeVoxels() {
+        return voxelsRuntime;
+    }
 };
diff --git a/src/world/generator/WorldGenerator.cpp b/src/world/generator/WorldGenerator.cpp
index a6a1fe7e..726467a0 100644
--- a/src/world/generator/WorldGenerator.cpp
+++ b/src/world/generator/WorldGenerator.cpp
@@ -7,7 +7,8 @@
 #include "content/Content.hpp"
 #include "voxels/Block.hpp"
 #include "voxels/Chunk.hpp"
-#include "world/generator/GeneratorDef.hpp"
+#include "GeneratorDef.hpp"
+#include "VoxelStructure.hpp"
 #include "util/timeutil.hpp"
 #include "debug/Logger.hpp"
 
@@ -47,6 +48,8 @@ WorldGenerator::WorldGenerator(
     });
 }
 
+WorldGenerator::~WorldGenerator() {}
+
 static inline void generate_pole(
     const BlocksLayers& layers,
     int top, int bottom,
@@ -119,8 +122,8 @@ std::unique_ptr<ChunkPrototype> WorldGenerator::generatePrototype(
     }
     return std::make_unique<ChunkPrototype>(
         ChunkPrototypeLevel::BIOMES,
-        nullptr, 
-        std::move(chunkBiomes));
+        std::move(chunkBiomes),
+        nullptr);
 }
 
 void WorldGenerator::generateHeightmap(
diff --git a/src/world/generator/WorldGenerator.hpp b/src/world/generator/WorldGenerator.hpp
index 2802baa6..d30d88f9 100644
--- a/src/world/generator/WorldGenerator.hpp
+++ b/src/world/generator/WorldGenerator.hpp
@@ -14,6 +14,7 @@ class Content;
 struct GeneratorDef;
 class Heightmap;
 struct Biome;
+class VoxelStructure;
 
 enum class ChunkPrototypeLevel {
     BIOMES, HEIGHTMAP
@@ -22,18 +23,19 @@ enum class ChunkPrototypeLevel {
 struct ChunkPrototype {
     ChunkPrototypeLevel level;
 
-    /// @brief chunk heightmap
-    std::shared_ptr<Heightmap> heightmap;
     /// @brief chunk biomes matrix
     std::vector<const Biome*> biomes;
 
+    /// @brief chunk heightmap
+    std::shared_ptr<Heightmap> heightmap;
+
     ChunkPrototype(
         ChunkPrototypeLevel level,
-        std::shared_ptr<Heightmap> heightmap, 
-        std::vector<const Biome*> biomes
+        std::vector<const Biome*> biomes,
+        std::shared_ptr<Heightmap> heightmap
     ) : level(level),
-        heightmap(std::move(heightmap)), 
-        biomes(std::move(biomes)) {};
+        biomes(std::move(biomes)),
+        heightmap(std::move(heightmap)) {};
 };
 
 /// @brief High-level world generation controller
@@ -49,6 +51,8 @@ class WorldGenerator {
     /// @brief Chunk prototypes loading surround map
     SurroundMap surroundMap;
 
+    std::vector<std::unique_ptr<VoxelStructure>> structures;
+
     /// @brief Generate chunk prototype (see ChunkPrototype)
     /// @param x chunk position X divided by CHUNK_W
     /// @param z chunk position Y divided by CHUNK_D
@@ -61,15 +65,15 @@ public:
         const Content* content,
         uint64_t seed
     );
-    virtual ~WorldGenerator() = default;
+    ~WorldGenerator();
 
-    virtual void update(int centerX, int centerY, int loadDistance);
+    void update(int centerX, int centerY, int loadDistance);
 
     /// @brief Generate complete chunk voxels
     /// @param voxels destinatiopn chunk voxels buffer
     /// @param x chunk position X divided by CHUNK_W
     /// @param z chunk position Y divided by CHUNK_D
-    virtual void generate(voxel* voxels, int x, int z);
+    void generate(voxel* voxels, int x, int z);
 
     inline static std::string DEFAULT = "core:default";
 };