The Mad Hatter (1940)

Maisie is a secretary. We watch her dashing to work, then sitting through a typical day, reading novels and eating candy. But that's all prelude, as she lives to shop, particularly for hats. She tries on a wide variety of hats, but her heart is set on #36, which she's told must be special ordered. She orders it, and we switch to the hat workshop, where we see the designers, all of them clearly insane. Number 36 is let out long enough to whip one up for Maisie.