Hi there :-) New on HN, first time posting.

Past year, around December, I started experimenting with making ChatGPT and Claude generate source code in LDraw language.

This LDraw is literally an "assembly" language, a low-level programming language that describes how to assemble LEGO pieces together into models, one placement instruction at a time.

When executed by specific tools, like e.g. LDView, LeoCAD, Studio... these instructions become LEGO CAD models, that can be interacted with, modified, etc.

Or, in other words: one LDraw source file in .mpd or .ldr format is equivalent to one LEGO CAD model.

So, the idea I had was: if I manage for maybe ChatGPT or Claude to generate high-quality LDraw source files... then, they would actually be generating high-quality LEGO CAD models, right?

Then, after months of iterations and trying one thing after the other... it worked!!!

Long story short: using GPT-6 Astra and Opus 5.5, I've managed to create a python toolset, instructions, and docs for agents in general. Now, these can be used by them to generate LDraw models.

I've packed it all as a dockerized web app for others to try and experiment, with several providers (and agents) to choose from: OpenAI, Claude and OpenRouter.

Here's a bunch of exmaples: https://anteloc.github.io/index-samples.html.

If you are curious about the internals of an .mpd model, the "what was the agent picturing on its mind", open the .mpd file that got your attention on a text editor, and read the first line under the ones starting with "0 FILE".

I'd really appreciate feedback and comments, let's see where this goes =)

user:	CptBroccoli
created:	October 2, 2026
karma:	1