Build .twpack Structures in Terraria with the TerraWorld Blueprints Mod

A .twpack from Structure Studio can already be pasted into a world with the map editor, but that skips the fun part of Terraria: gathering materials and building. TerraWorld Blueprints is a small tModLoader mod that brings the package into the game instead. It projects the structure as a ghost over your world, tells you which item every cell needs, and can build the whole thing for you once you have paid for it with real items.

The mod is an open example of how to read the .twpack format, and its source code is public on GitHub. It is free to use, but it is maintained on a best-effort basis, so back up your world before trying a large blueprint.

What you need

• Terraria with tModLoader.
• The TerraWorld Blueprints mod, from the Steam Workshop. It is also listed on Nexus Mods. In tModLoader, open Workshop → Download Mods, search for TerraWorld Blueprints, install it, and enable it in Workshop → Manage Mods.
• At least one .twpack file. Design one in Structure Studio, let an AI design it with the AI guide, or open the sample castle and export it.

Step 1: Put your blueprints in the mod folder

Export the structure with Export .twpack and copy the file into:

Documents/My Games/Terraria/tModLoader/TerraWorldBlueprints/

You do not have to find this folder yourself. Once you have the Blueprint Tablet, its panel has an Open folder button that opens it, and a Reload button that rescans it after you add new files. A blueprint that needs tiles from mods you have not enabled is marked with the missing mods.

Step 2: Craft the Blueprint Tablet and project a blueprint

Craft a Blueprint Tablet from 10 Wood at a Work Bench.

1. Hold the tablet and right-click to open the Blueprints panel, then pick a file under Blueprint files.
2. Close the panel and move the cursor to where the structure should stand. The cursor marks the bottom centre of the structure, so point at the ground you want it to rest on.
3. Left-click to project it. The cursor preview disappears after one placement; pick the blueprint again to place another copy.

Projections are saved with the world. The panel lists them under Projected in this world, where Remove deletes one you no longer need.

Step 3: Read the ghosts

The projection shows only what is still left to build:

• Blue cells still need building.
• Red cells are blocked by a block or wall that is already there. The mod never destroys anything, so clear these cells yourself.
• Finished cells disappear from the ghost.

Hover over a ghost cell to see the item that places it and a count such as Gray Brick 120 / 340: how many you carry against how many the blueprint still needs. Tiles that no item can place, such as grass, pots, or natural walls, are marked as skipped.

Step 4: Build by hand, layer by layer

Building by hand works exactly like normal Terraria: place the right item on each blue cell. A few panel options make large builds easier:

• Blocks, Walls, and Liquids show or hide each part of the ghost, so you can lay the background walls first and then the blocks.
• Ghosts: on/off hides every projection while you look around.
• Build layer by layer shows one band of rows at a time, counted from the bottom of the nearest projection. Choose how many Rows a layer has, step with Up and Down, or jump to the Lowest unfinished layer.
• PageUp and PageDown step through the layers without opening the panel. Change them under Settings → Controls → Mod keybinds (Blueprint layer up and Blueprint layer down).

Step 5: Let the Blueprint Builder do the work

Craft a Blueprint Builder from 20 Wood, 5 Iron or Lead Bars, and a Blueprint Tablet at an Anvil, and place it near the projection.

1. Right-click the Builder and choose a projection under Choose a projection to build.
2. The panel lists Materials (stored / needed). Use Take materials from to choose the sources: your Inventory, your Piggy Bank, Safe, Defender's Forge, and Void Vault, and the nearest Magic Storage network when that mod is enabled.
3. Press Pull materials. Items are taken in that order, and favourited items are never taken.
4. As soon as everything is paid for, the Builder starts placing cells. Build now starts it manually, Withdraw returns stored materials, and Unlink detaches the Builder from the projection.

Every cell is paid for with the item that places it, including paint, coatings, wires, and actuators. When cells are blocked, the Builder tells you how many, and it skips cells that have no item unless the server allows them.

Mod settings

Open Settings → Mod Configuration → TerraWorld Blueprints. The settings are server-side, so in multiplayer the host decides them:

• Place tiles with no item for free: lets grass, pots, natural walls, and similar tiles be placed without payment. Off by default.
• Place liquids: each liquid cell costs one water, lava, or honey bucket. Off by default.
• Build speed (cells per second): how fast the Builder places paid-for cells. The default is 40.
• Ghost opacity: transparency of projections in percent. The default is 30.

Things to know

• Chest contents are never copied. A blueprint builds the chest, its name, and sign text, but not the items, so blueprints cannot duplicate loot.
• Multiplayer: the mod must be installed on the server and every client. Ghosts and building by hand work for everybody; the Blueprint Builder works in single-player only in this version.
• Modded tiles in a blueprint need their mods enabled. Their tile entities are not recreated.
• The tablet panel has Open TerraWorld and Open Structure Studio buttons, so you can design or adjust a build without leaving the game for long.
• The mod's text is in English for now.

Troubleshooting

• "No .twpack files yet": the file is not in the TerraWorldBlueprints folder, or the panel needs Reload.
• "Right-click the Blueprint Tablet to choose a blueprint first": pick a file in the panel before left-clicking in the world.
• Many red cells: the structure overlaps terrain. Remove the projection, dig or flatten the area, and project it again, or clear the red cells by hand.
• Builder stops early: check the materials list for missing items and the panel for blocked cells. Favourited items in your inventory are never used.

Building the mod from source

The source code is on GitHub at CrabPlayer/TerraWorldBlueprint. Bug reports and pull requests are welcome there.

1. Open Workshop → Develop Mods in tModLoader once. This creates ModSources/tModLoader.targets.
2. Clone or download the repository into ModSources/TerraWorldBlueprint.
3. Build it from the Develop Mods menu, or run dotnet build in that folder while tModLoader is closed.

The repository's README also documents the .twpack format, in case you want to support it in your own mod.

Related Guides

• Design and Share Terraria Builds with Structure Studio

  Design Terraria structures on a dedicated canvas, work safely with layers, and export an open .twpack package that can be shared, placed in a world, or supported by a mod.

• Design Terraria Structures with AI and Export Them as .twpack

  Ask ChatGPT, Claude, or Gemini for a Terraria build, open its link in Structure Studio, check it in Real View, send the problems back to the AI, and export a .twpack. It works in a browser, even on a phone.

• Export, Share, and Import Terraria Builds with Structure Studio

  Turn a selected build into a reusable package, choose exactly which data it contains, and add imported structures to the editor clipboard for placement.