>>1548604https://www.history.com/topics/vietnam-war/cu-chi-tunnelsCheck it out bro. These people were highly adaptive and talented. They acted like a homogeneous group to fight off destructive foreign occupation.
A movie projector can be a small thing, easily transported and maintained. The fact that work began on these tunnels in the 1940s means that by the time of the American occupation they could have been quite sophisticated.