Wouldn’t it be easier to just build the factory in the mountain and leave it there?
.Bombproof Plane Factories ROLL INTO MOUNTAIN SIDE
Raid Shelters for Assembly Plants: A Swiss Inventor’s Solution to the Problem of Protecting Production AIRPLANE FACTORIES that literally run to shelter from raiding bombers have been invented by Antoine Gazda, noted Swiss armament designer, and erected at undisclosed places in Switzerland by the Pilatus aircraft concern as a national-defense precaution. A typical installation consists of a pair of twin assembly plants, normally standing in the open where their total of 360 workers enjoy natural sunshine and fresh air.

























