Prison Girls enhanced its exploitable potential by adding 3-D to the mix. Invented in 1838, stereoscopy was applied to create the illusion of a third dimension. Although used in film by the Lumière brothers as early as 1903, it really took off in the 1950s with the success of United Artists' Bwana Devil (1952). Although expensive, 3-D was a gimmick that could be put to use to capture audiences: a perfect device for otherwise average exploitation flicks like Prison Girls.