3MM File

What are 3MM files and how to open them

Are you having problems opening a 3MM file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your 3MM files.

What is a 3MM file?

A .3MM file is a 3D Movie Maker file.

3D Movie Maker (.3MM) files are the project files used by Microsoft's creative program 3D Movie Maker. They store everything needed to build an animated 3-D "movie" inside the program: character and prop placements, background scenes, camera angles, dialogue, sound effects, music, visual effects, text, and timing of all these elements. These files do not contain the final video frames themselves, but rather instructions and references to assets (models, backgrounds, sounds) that are stored elsewhere.

The .3MM format replaced the older .vmm format in later versions of the software. When a user works in 3D Movie Maker and saves their work, the program writes a .3MM file, which can then be re-opened and edited later. Although .3MM files are "movies" in the sense of editable animated sequences, the program does not export them directly as movie files like AVI; instead, the .3MM file remains a project file used for editing and playback within 3D Movie Maker.

Internally, .3MM and related data files are made up of binary "quads," or data blocks each marked with four-letter identifiers that specify the type of content contained. The file begins with the ASCII signature "CHN2" found at the very start (offset zero), which identifies the file as a 3D Movie Maker data/project file.

How to open 3MM files

Important: Different programs may use files with the 3MM file extension for different purposes, so unless you are sure which format your 3MM file is, you may need to try a few different programs.

While we have not verified the app ourselves yet, our users have suggested a single 3MM opener which you will find listed below.

Last updated: August 16, 2026

Various apps that use files with this extension

These apps are known to open certain types of 3MM files. Remember, different programs may use 3MM files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about 3MM file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.