How to Build Your Own LEGO® Prop Locker with Verse

Ever play a LEGO® Fortnite island where you collect blueprints, unlock new furniture, and then go build a mansion? That magic doesn’t happen by accident. It’s run by a hidden "manager" that keeps track of every brick, tree, and trap you’re allowed to spawn.

In this tutorial, we’re going to build that exact system. We’ll set up a LEGO® Grid Entity Manager—the brain of your build zone—and learn how to feed it a list of props (like a loot pool) and unlock packs (like a battle pass for buildings). By the end, you’ll have a working inventory system where players can unlock new items to place on their grid.

What You'll Learn

• The Scene Graph vs. The Grid: Why the objects in your build menu are different from the objects in your world.
• Entity Managers: How to use a Verse device to act as the "inventory controller."
• Unlock Packs: How to gatekeep cool props behind quests or achievements.
• Grid Definitions: How to tell the game which props are actually buildable.

How It Works

To understand this, you need to separate two concepts that usually get mixed up: The Scene Graph and The Build Grid.

1. The Scene Graph (The World)

Think of the Scene Graph as your actual Fortnite island. It’s the hierarchy of everything that exists in the 3D world: the trees, the enemies, the loot boxes, and the players. When you place a prop in UEFN, it becomes part of the Scene Graph. It’s real. It’s solid. It can be destroyed.

2. The Grid Entity (The Menu)

Now, think of the LEGO® Grid. This isn’t part of the Scene Graph in the same way. It’s a system. The Grid Entity is a placeholder definition. It’s like a blueprint in your backpack. Before you build a wall, that wall exists only as data in your inventory. It’s not in the world yet. It’s just a possibility.

The LEGO® Grid Entity Manager is the device that holds the list of these blueprints. It’s your inventory screen. It says, "Here is a list of things you can build."

3. Unlock Packs (The Battle Pass)

Not every prop should be available from the start. You want players to work for the good stuff. Unlock Packs are groups of Grid Entities that are locked until a condition is met (like completing a quest or finding a key). The Manager checks these packs to decide what to show in the build menu.

4. The Workflow

1. Define the Prop: You take a 3D model (a tree, a turret, a chair) and tell the system, "This is a buildable item."
2. Add to Manager: You drop that item into the LEGO® Grid Entity Manager device.
3. Assign to Pack: You put that item into an "Unlock Pack" (e.g., "Basic Pack" or "Advanced Pack").
4. Player Interaction: When the player completes the requirement, the Manager unlocks the pack, and the prop appears in their build menu.

Let's Build It

We aren't writing raw Verse code from scratch here; we’re configuring a Verse Device in UEFN. Think of the device as a pre-written script that you fill in the blanks for. It’s like configuring a Trap in Creative: you don’t write the code for the explosion, you just set the trigger.

Here is the step-by-step setup for a basic LEGO® Grid Entity Manager.

Step 1: Create the Manager Device

1. Open UEFN.
2. Go to the Devices panel.
3. Search for LEGO® Grid Entity Manager.
4. Drag it into your level (it can be anywhere; it doesn’t need to be visible).

Step 2: Define Your Grid Entities

This is the core of the tutorial. We need to tell the Manager what props are allowed.

1. Select the LEGO® Grid Entity Manager device.
2. In the Details panel, look for Grid Entities.
3. Click the + button to add a new entry.
4. Grid Entity Name: Give it a simple name, like MyCoolTree.
5. Prop Asset: Click the browse button and select a 3D prop from your library (e.g., a Prop_Tree_Oak).
6. Size: Set the grid size (e.g., 1x1, 2x2). This determines how many "studs" it takes up on the build grid.

Pro Tip: If you want a prop to be huge (like a castle), make sure your grid size matches its dimensions. If you try to place a 4x4 prop on a 1x1 grid slot, it won’t fit.

Step 3: Create an Unlock Pack

Let’s say MyCoolTree is rare. We want players to earn it.

1. In the same Details panel, look for Unlock Packs.
2. Click the + button to add a new pack.
3. Pack Name: Basic_Pack.
4. Add to Pack: Drag MyCoolTree from your Grid Entities list into this pack.
5. Requirement: You can link this to a Quest or a simple boolean flag. For now, let’s keep it simple: we’ll assume this pack is unlocked by default for testing.

Step 4: Connect the UI (The Input)

The Manager doesn’t do anything unless the player interacts with it.

1. Place a LEGO® Grid device in your level (this is the actual build zone).
2. In the Details panel for the LEGO® Grid device, look for Manager.
3. Drag your LEGO® Grid Entity Manager from Step 1 into the Manager slot.
4. Now, the Grid knows where to pull its inventory from.

Step 5: Test It

1. Press Play.
2. Approach the LEGO® Grid device.
3. Open the build menu.
4. You should see MyCoolTree in your list.
5. Place it!

If you want to test the Unlock Pack logic:

1. Create a Quest device.
2. Set the quest objective to "Collect 10 Shells."
3. Set the reward to "Unlock Pack: Basic_Pack."
4. Link the Quest to the LEGO® Grid Entity Manager (usually via a Verse script or a simple trigger).
5. Now, the tree only appears in the menu after the quest is done.

The Verse Behind the Curtain

Even though we’re using a device, it’s powered by Verse. Here’s what’s happening under the hood, written in pseudo-Verse logic, to help you understand the structure:

# This is a simplified representation of what the device does

struct GridEntity {
    Prop: PropAsset      # The 3D model
    Name: string         # "MyCoolTree"
    Size: vector2        # 1x1, 2x2
}

struct UnlockPack {
    Entities: list<GridEntity> # List of allowed props
    IsUnlocked: bool           # True if player earned it
}

class GridEntity_Manager {
    # The list of all possible props
    Available_Props: list<GridEntity>
    
    # The list of packs
    Packs: list<UnlockPack>
    
    # Function called when player opens build menu
    function Get_Buildable_Props(Player: Player) -> list<GridEntity>:
        Result: list<GridEntity> = []
        
        for Pack in Packs:
            if Pack.IsUnlocked:
                # Add all props in this pack to the result
                for Entity in Pack.Entities:
                    Result.Add(Entity)
                    
        return Result
}

The device handles the Get_Buildable_Props function for you. You just feed it the PropAsset and set the IsUnlocked flag via your quest system.

Try It Yourself

Challenge: Create a "Trap Shop" system.

1. Add three different trap props (e.g., a Spike Trap, a Fire Trap, and a Bouncer) to your LEGO® Grid Entity Manager.
2. Create two Unlock Packs:
   • Free_Pack: Contains only the Spike Trap.
   • Premium_Pack: Contains the Fire Trap and Bouncer.
3. Set up a simple trigger: When a player steps on a specific tile, it unlocks Premium_Pack.
4. Test it: Can you place the Spike Trap immediately? Does the Fire Trap disappear from the menu until you step on the tile?

Hint: You don’t need to write code to make the trigger work. Use a Trigger Volume device connected to a Set Boolean or Quest device to flip the IsUnlocked state of the pack.

Recap

• Grid Entities are blueprints for props, not actual 3D objects in the world.
• The LEGO® Grid Entity Manager is the device that holds your inventory of buildable items.
• Unlock Packs let you gatekeep props behind quests or achievements.
• Connect the Manager to a LEGO® Grid device to let players actually build with the items.

You’ve now built the backbone of any LEGO® style building island. From here, you can expand into complex crafting systems, economy-driven builds, or even multiplayer co-op building challenges. The grid is your canvas, and the Manager is your paintbrush.

References

• https://dev.epicgames.com/documentation/en-us/fortnite/setting-up-the-lego-grid-entity-manager-in-unreal-editor-for-fortnite
• https://dev.epicgames.com/documentation/en-us/fortnite/creating-a-lego-grid-placement-system-in-unreal-editor-for-fortnite
• https://dev.epicgames.com/documentation/en-us/fortnite/lego-bloom-tycoon-levels-and-devices-in-unreal-editor-for-fortnite
• https://dev.epicgames.com/documentation/en-us/fortnite/lego-bloom-tycoon-in-fortnite
• https://dev.epicgames.com/documentation/en-us/fortnite/configuring-lego-prop-placement-in-unreal-editor-for-fortnite