Chinese Type 65 Gas Mask Dummy Filter Unit

I made this 3D model after hearing that asbestos is used in the filters of old gas masks (according to r/gasmasks on Reddit, it's actually not that dangerous).

This dummy is designed to remove the built-in filter of the Chinese People's Liberation Army's Type 65 gas mask and put in its place. A 3D model of a ventilation unit with a built-in 30mm x 30mm electric fan is also available as an option. However, please devise your own electrical wiring and switches.

*The polygons of the 3D model are not smart at all, as I made heavy use of Blender's boolean modifier.