Desktop app · beta

Danish Bricks Builder for Mac and Windows

A small desktop app for building brick models with an AI agent. It shows your models in 3D, checks that they hold together, and lets the coding agent you already use do the building.

This is a beta. It is an early version from a one-person project: expect rough edges, things that break. Your models are plain files on your own computer, so nothing you build is at risk.

Looking for the current build…

What it does

See: Open any folder of LDraw models (.ldr, .mpd). Step through the build, explode it, cut it open, hide parts, set an exact camera angle.
Build: Ask Claude Code or Codex for a model in plain words. The agent searches parts, measures them, writes the file and renders it to check its own work while you watch.
Check: Find parts that collide, float or only almost connect. List the rigid bodies, turn joints and gear trains, and see what moves with what.
Keep: A build is a folder of plain files on your computer. Nothing is uploaded.

Install

1
Download and install
Download the disk image above and double-click it. In the window that opens, drag Danish Bricks Builder onto the Applications folder.
2
Open it the first time
Open it from Applications. macOS asks once whether to open an app downloaded from the internet: click Open. The app is signed and checked by Apple, so there is nothing to approve in System Settings.
3
Get the parts
On first launch, click Download parts library in the top bar. It fetches the official LDraw library (about 150 MB) from library.ldraw.org. If you already have LDraw on your computer, the app finds it.
4
Start a build
Click New build, give it a name, and describe what you want in the chat. The app runs the Claude Code or Codex you already have installed and signed in; it has no account or key of its own.

What you need

A Mac with Apple silicon (M1 or newer), or a 64-bit Windows 10 or 11 PC (new, beta). Intel Macs and Linux are not built yet.
Node.js 20 or newer, for the model tools (rendering for the agent, part lookup).
To build with an agent: Claude Code or Codex, installed and signed in. Viewing and editing files works without either.

Known limits of this early build

The collision and motion checks download their part data the first time you run one (about 30 MB, then a little per model), so the first check needs an internet connection.
From version 0.4.0 the app tells you when a newer version is out and updates itself when you say so. Older copies do not: download again from this page once.

LEGO® is a trademark of the LEGO Group, which does not sponsor or endorse this app. Part geometry comes from the LDraw parts library.