When I’m writing about the Twenties, my fictional women can dry their bobbed hair at home with a vacuum cleaner. Or a toaster.
While the very first electric hair dryer seems to have been invented by a French hairdresser in the 1890s, it was a heavy, stationary piece of machinery that he used in his salon, not something available to women in their homes. The first time most women had access to a hair dryer was in the Twenties when some nameless person figured out how to rejigger the vacuum cleaner into a hair dryer. By modifying the vacuum with an attachment or making one yourself, you could have your own hair dryer. Vacuum cleaners, by the way, were just beginning to be popular with middle-class women at this time. Articles like the one below from 1933 told how you could make your own attachment and get double duty from your vacuum.
An issue of Popular Mechanics Handbook for Women from 1924 instructs you on how to make a hair dryer from a vacuum cleans and an electric toaster.