Notes about the 3CN file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The 3CN file type is primarily associated with '3D Movie Maker' by Microsoft Corporation. Main data file in 3DMM. Used for actors, props, 3D words, scenes, and sounds. Identified by the header: CHN2 (used by all 3DMM files).