PrefabKit
Reusable, nestable, randomizable prefabs

Overview

PrefabKit adds prefabs to Unreal Engine 4.27 and 5.8. A prefab is an asset that stores a group of actors together with their properties and their transforms relative to a pivot. A APrefabKitActor placed in a level builds those actors as its attached children. Edit the children of any instance, save them back to the asset, and every other instance in the level is rebuilt.

• Create a prefab from the current selection with one click; a thumbnail is captured automatically.
• Nested prefabs: a prefab can contain other prefab actors.
• Prefab collections: weighted lists of prefabs; each placed actor picks one entry from its own seed.
• Randomizer and Seed Linker actors for re-rolling a whole level or a chosen set of prefabs.
• Blueprint and C++ API to spawn, randomize, re-assign and unlink prefabs at runtime.
• Runtime construction system: ghost cursor, snap points for floors, walls and objects, build and remove tools, a build menu widget and save/load of player-built levels.

Requirements

Installation

1. Install PrefabKit from Fab into your engine, or copy the PrefabKit folder into your project's Plugins folder.
2. For a C++ project, regenerate project files and build the editor target.
3. Open the project, enable PrefabKit in Edit > Plugins and restart the editor.
4. C++ only: add the modules you use to your Build.cs, for example PublicDependencyModuleNames.Add("PrefabKitRuntime"); and, for the construction system, "PrefabKitConstructionRuntime".

Quick start

Create and place a prefab (editor)

1. In the Content Browser, select the folder where the new asset should go.
2. Select a few actors in the level and click PrefabKit > Create Prefab (from selection) in the toolbar (or right-click in the viewport).
3. A prefab asset is created and the actors are attached under a new APrefabKitActor.
4. Move, add or change child actors, select the prefab actor and press Save Prefab to Asset in the Details panel.
5. Drag the prefab asset from the Content Browser into the level to place more instances.

Spawn a prefab at runtime (Blueprint)

1. Add a variable of type UPrefabKitAssetInterface (object reference) and set it to a prefab or prefab collection.
2. Call Spawn Prefab with a world context, the asset, a transform and a seed.
3. Use the returned prefab actor with Randomize Prefab, Set Prefab Asset or Unlink Prefab.

C++

// Build.cs: PublicDependencyModuleNames.Add("PrefabKitRuntime");
#include "Utils/PrefabKitFunctionLibrary.h"
#include "Asset/PrefabKitAsset.h"
#include "Prefab/PrefabKitActor.h"

// In AMyActor: UPROPERTY(EditAnywhere) TSoftObjectPtr<UPrefabKitAssetInterface> PrefabToSpawn;
void AMyActor::SpawnRoom()
{
    if (UPrefabKitAssetInterface* Prefab = PrefabToSpawn.LoadSynchronous())
    {
        APrefabKitActor* Room = UPrefabKitBlueprintLibrary::SpawnPrefab(this, Prefab, GetActorTransform(), /*Seed*/ 1234);
        if (Room)
        {
            FRandomStream Stream(42);
            UPrefabKitBlueprintLibrary::RandomizePrefab(Room, Stream); // pick new variations and rebuild
        }
    }
}

Editor workflow

Toolbar menu and context menus

Details panel buttons

Prefab assets & actors

Blueprint library

Static nodes in UPrefabKitBlueprintLibrary (category PrefabKit).

Randomization

Construction system

The construction system lets players place and remove prefabs at runtime. Add a UPrefabKitConstructionComponent to your Player Controller, assign Build Menu UI (for example ConstructionSystem/UI/PKBuildMenu) and Build Menu Data (a UPrefabKitConstructionUIAsset), and place UPrefabKitConstructionSnapComponent components inside the prefabs players can build.

Input mappings

The component binds these legacy input names (add them under Project Settings > Input):

Construction component

Tools

Snapping

Build menu

Saving player-built levels

Settings

Project Settings > Plugins > PrefabKit (stored in DefaultPrefabKit.ini).

Content

Troubleshooting

Credits

© 2026 Alpha XP — alphaxp.net · Support: support@alphaxp.net. Built and verified for Unreal Engine 4.27 and 5.8.