An MWM file contains a 3D model used by Space Engineers, a sandbox game used to engineer and construct spaceships to explore and survive space and planets. It stores 3D object appearance information, such as the vertices, length, and shininess. MWM files are used for various types of objects in the game, which include characters, tools, weapons, and spaceships.

You will most likely only encounter an MWM file if you play Space Engineers and are looking to modify objects in the game. Models can be found in the following directory: \Steam\SteamApps\common\SpaceEngineers\Content\Models MWM files store appearance information for various types of 3D objects, such as machine guns, angle grinders, automatic rifles, and hand drills.