MM3D
From Just Solve the File Format Problem
MM3D (Misfit Model 3D) is the format saved by an OpenGL-based 3D model editor that was in open-source development from 2004 to 2009, with an anouncement in 2011 that it was no longer under active developmennt.
FIle Identification
MM3D files have the header 4D 49 53 46 49 54 33 44
("MISFIT3D").