>>509623321
Just to reiterate here - this is the inside of an F1 engine, one of 5 on the Saturn V
That round object is the injector plate, where the liquid fuel and oxygen were sprayed to get thrust
They were drilled by hand

The long pipes down the size held the fuel/oxygen before it went into the injector plate (because it helped keep the engine bell cool)
Those were welded by hand by the best skilled welders they could find

Basically the entire manufacturing power of the USA was at NASA's disposal, and they used it to do something spectacular
Not once, but 6 times.