What is a PART file & how do I open a PART file (PartDesigner Part)?

.PART (PartDesigner Part) - File Extension

Developer: The LEGO Group

What is a PART file?

A “.PART” file represents a custom LEGO design created in specific software called LEGO PartDesigner. Within this file, you’ll find details about unique LEGO pieces and how they fit together, allowing enthusiasts to craft and share their own LEGO creations digitally.

A “.PART” file is essentially a digital container that can hold information. At its core, it’s a file extension, much like how documents might end in “.doc” and images in “.jpg.”

In the world of downloads, a “.PART” file usually indicates a partially downloaded file. When you’re downloading something, the software might first save it as a “.PART” file, and only when the download is fully complete does it get its proper extension. This ensures that you don’t mistakenly open an incomplete file.

How to open a PART file

Program Association: To open a PART file, you primarily require LEGO PartDesigner, a tool developed for the LEGO community to design custom parts.

Steps to Open:

  1. Installation: Start by installing LEGO PartDesigner.
  2. Navigate: Once installed, navigate to the ‘File’ menu and choose ‘Open.’
  3. Select File: Browse to the location of your PART file and select it.
  4. View & Edit: The file will open, allowing you to view and modify the custom LEGO part.

How to convert a PART File

Conversion of a PART file to other formats or vice versa isn’t a widespread need, but there are a few scenarios to consider:

  1. To Image Format: You might want a visual representation of your design. In this case, use the “Export” feature in PartDesigner, which can save the design as an image file.
  2. To Other LEGO Design Files: Some third-party tools or scripts might facilitate the conversion, but ensure to check for data fidelity.

Always be cautious and backup your original PART file before conversion.

Security Considerations: Are “.PART” Files Safe?

As with any file, security is paramount. “.PART” files, in the context of LEGO designs, are generally safe as they contain plain text data regarding LEGO bricks. However, always:

  • Scan: Before opening any file, especially those downloaded from the internet, scan it with updated antivirus software.
  • Source Verification: Only download or receive PART files from trusted sources.

Format Details for PART Files

Being a format primarily associated with LEGO PartDesigner:

  • Content Structure: PART files store data in plain text format, specifying the LEGO bricks and elements the part comprises.
  • File Size: The file size is relatively small due to its textual nature, but it can vary based on the complexity of the design.

Uses and Applications of PART Files

PART files find their primary use among LEGO aficionados:

  • Custom Design Creation: They allow users to build custom LEGO parts not available in the standard set.
  • Project Integration: These custom parts can be integrated into larger LEGO BrickLink building projects.

Associated Software Programs

  • LEGO PartDesigner: This is the primary software for creating, editing, and viewing PART files.
  • LEGO BrickLink: While not directly opening PART files, this platform can utilize the parts contained within these files for larger projects.

Advantages and Disadvantages of PART Files


  • Customization: Enables users to design parts beyond standard LEGO offerings.
  • Compact Size: Being text-based, these files are lightweight.
  • Integration: Easily integrates with LEGO BrickLink projects.


  • Limited Software Support: Primarily supported by LEGO PartDesigner.
  • Learning Curve: Requires understanding of the LEGO design ecosystem.


PART vs. LXF: While PART files focus on individual LEGO parts, LXF files (LEGO Digital Designer) encompass entire LEGO designs, offering a broader view.

Troubleshooting PART Files

  1. File Doesn’t Open: Ensure LEGO PartDesigner is correctly installed and updated.
  2. Corruption Issues: Always keep backups. Corrupt files may not be recoverable, but third-party tools could offer some help.

History of the PART File Extension

The PART file extension’s inception is intertwined with the growth of the LEGO enthusiast community. As users demanded more customization, LEGO PartDesigner was developed, giving birth to the PART file. Over the years, its usage among the community has grown, though its fundamental design remains largely unchanged.

Tips and Tricks for PART Files

  • Backup: Always keep backups of your designs.
  • Online Communities: Join LEGO forums to learn and share new tricks.
  • Update Software: Regularly update LEGO PartDesigner for the best experience.

Extended Details and Misconceptions about PART Files

It’s worth noting that the “.PART” extension has been known to the general public primarily as a temporary file extension used by many software applications, especially download managers, indicating that a download is in progress.

Only when the download is complete will the “.PART” extension be removed, revealing the true format of the downloaded file. This has sometimes led to confusion with the LEGO “.PART” file.

It’s essential to understand the context in which the file is being discussed to avoid misunderstandings.

Interoperability with Other LEGO Software

While LEGO PartDesigner primarily deals with “.PART” files, there are several other LEGO-oriented software tools available.

It’s crucial to comprehend the interoperability between these software solutions.

For instance, while direct conversion might not always be possible, understanding the standard building blocks between programs can enable savvy users to replicate designs across platforms manually.

Potential for 3D Printing

With the rise of 3D printing, there’s potential for “.PART” files to play a role in the realm of 3D LEGO design and printing.

Enthusiasts may explore options for converting “.PART” designs into formats acceptable by 3D printers, paving the way for truly customized physical LEGO pieces.

Community-Driven Enhancements

The beauty of specialized file types like “.PART” in the context of LEGO lies in the community around them.

Users often develop scripts, plugins, and other tools to extend the functionality of the primary software, offering features not available out-of-the-box.

It’s always a good idea to be active in the community forums to keep abreast of such developments.

Open-Source Alternatives

As with many niche software applications, there’s always a potential for open-source alternatives to emerge.

While LEGO PartDesigner is the de facto choice for “.PART” file creation and editing, LEGO enthusiasts may find open-source solutions that offer compatibility or alternative features.

Always ensure that such software is from trusted sources and that there’s a robust community behind it to ensure its longevity and security.


The “.PART” file extension, while seemingly straightforward, is a testament to the power of community-driven innovation.

By allowing LEGO aficionados to venture beyond standard sets and into the realms of their imagination, PART files have become an essential tool in the LEGO digital design toolkit.

Whether you’re a seasoned LEGO designer or a newbie just dipping your toes, understanding the intricacies of the PART file can unlock a world of creative possibilities.

Software Compatible With The PART File Type
PartDesigner Part

In this section you will find a list of the best programs compatible with the PART file type. We've selected the best software for Windows, Mac, Android and Linux to open, edit, convert and view the contents of PART files.