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I want to 3D print my LEGO models (.lxf file type). How do you do it?

Do you export it to a specific file type (there are LXFML, LDraw, and LXFML4 besides LXF) then import into a 3D modeller?

Or is there a way to 3D print directly from LEGO Digital Designer?

Can you save all parts used in the model automatically (not manually by hand, it will be too much work) in a 3D-printable file format then print those parts individually?

I really don't know anything about 3D printing, so please share if you know anything that could help!

  • It's a cool idea but even with the best 3D printer you're unlikely to match the tight tolerances that LEGO bricks (made using plastic moulds) have. – Ambo100 Apr 1 '17 at 17:34
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First, some notes:

  • LEGO Digital Designer cannot do 3D printing.
  • LDD won't get any new features any time soon, as it is no longer being updated.
  • LXF files contain no part meshes. They only contain information on how to assemble the parts. The actual part data is stored in binary files inside the various LIF files.
  • LDraw files are similarly structured like the LXF files.

So getting 3D mesh data out of LDD is tricky to say the least. I know of two techniques:

  1. There is some software which will attempt to capture 3D mesh from memory. Caveats:

    • LDD optimizes the drawing by removing the faces of parts that are not visible.
    • This means the mesh you get out may be missing some things you might expect.
  2. Convert to LDraw, and open in an LDraw compatible program that can export 3D meshes. This is probably your better option, but it also has some caveats:

    • If you are using a piece that your LDraw program does not have in the library, it will be missing.
    • If LDD does not know how to map a part to LDraw, it could also be missing.

I know some people have done some research into directly converting LDD models directly into 3D mesh, by reverse engineering the file formats. I don't know of any complete tools that actually do this though.

Now for the next issue, once you have your 3D mesh into another program, is it good for printing? Even without knowing specifics, I doubt it. Modelling for 3D printing is a lot different from modelling from LEGO bricks. You would likely have to do a lot of work making the model printable. It would probably be quicker to make the model from scratch in the 3D modelling program directly.

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