diff --git a/libs/ecs/include/psemek/ecs/container.hpp b/libs/ecs/include/psemek/ecs/container.hpp
index c9e31370..1a8b24fa 100644
--- a/libs/ecs/include/psemek/ecs/container.hpp
+++ b/libs/ecs/include/psemek/ecs/container.hpp
@@ -364,6 +364,9 @@ namespace psemek::ecs
 		template <typename Index, typename ... Args>
 		Index & index(Args && ... args);
 
+		template <typename Index, typename Factory>
+		Index & index_factory(Factory && factory);
+
 		template <typename ... Components>
 		std::size_t memory_usage();
 
@@ -767,6 +770,12 @@ namespace psemek::ecs
 		return index_container_.get<Index>(*this, std::forward<Args>(args)...);
 	}
 
+	template <typename Index, typename Factory>
+	Index & container::index_factory(Factory && factory)
+	{
+		return index_container_.set<Index>(std::move(factory));
+	}
+
 	template <typename ... Components>
 	std::size_t container::memory_usage()
 	{
diff --git a/libs/ecs/include/psemek/ecs/detail/index_container.hpp b/libs/ecs/include/psemek/ecs/detail/index_container.hpp
index a13bdbe5..d0e71160 100644
--- a/libs/ecs/include/psemek/ecs/detail/index_container.hpp
+++ b/libs/ecs/include/psemek/ecs/detail/index_container.hpp
@@ -4,6 +4,7 @@
 #include <psemek/util/hash_table.hpp>
 #include <psemek/util/type_name.hpp>
 #include <psemek/util/exception.hpp>
+#include <psemek/util/function.hpp>
 
 #include <memory>
 
@@ -24,19 +25,21 @@ namespace psemek::ecs::detail
 		{
 			auto uuid = Index::uuid();
 			if (auto it = storage_.find(uuid); it != storage_.end())
-				return *reinterpret_cast<Index *>(it->second.get());
+				return *reinterpret_cast<Index *>(it->second());
 
 			if constexpr (std::is_constructible_v<Index, ecs::container &, Args && ...>)
 			{
-				auto ptr = std::make_shared<Index>(container, std::forward<Args>(args)...);
-				storage_.insert({uuid, ptr});
-				return *ptr;
+				auto ptr = std::make_unique<Index>(container, std::forward<Args>(args)...);
+				auto result = ptr.get();
+				storage_.insert({uuid, [ptr = std::move(ptr)]{ return ptr.get(); }});
+				return *result;
 			}
 			else if constexpr (std::is_constructible_v<Index, Args && ...>)
 			{
-				auto ptr = std::make_shared<Index>(std::forward<Args>(args)...);
-				storage_.insert({uuid, ptr});
-				return *ptr;
+				auto ptr = std::make_unique<Index>(std::forward<Args>(args)...);
+				auto result = ptr.get();
+				storage_.insert({uuid, [ptr = std::move(ptr)]{ return ptr.get(); }});
+				return *result;
 			}
 			else
 			{
@@ -44,8 +47,20 @@ namespace psemek::ecs::detail
 			}
 		}
 
+		template <typename Index, typename Factory>
+		Index & set(Factory && factory)
+		{
+			auto uuid = Index::uuid();
+			if (storage_.contains(uuid))
+				throw util::exception("Index " + util::type_name<Index>() + " is already set");
+
+			auto result = factory();
+			storage_[Index::uuid()] = std::move(factory);
+			return *result;
+		}
+
 	private:
-		util::hash_map<util::uuid, std::shared_ptr<void>> storage_;
+		util::hash_map<util::uuid, util::function<void*()>> storage_;
 	};
 
 }