Women here on the Leelanau Peninsula did indeed used to hand-dip condoms during the 1920s and even into the 30s. It was based on a recipe created by a German named Julius Fromm. Women hand-dipped for two reasons.

1) The commercial varieties at the time were lousy. That remained the case until the 1930s.

2) Commercial condoms were hard to come by. The Comstock Act of 1873 was being enforced at the time. It criminalized the mailing or shipping of obscene materials and products intended for abortions. Condoms fell into those categories. Yes, condoms still moved around. Truckers occasionally brought packages up from Chicago, though they weren't on the bills of lading. The packages would make their way to taverns, where they'd be kept hidden under the bar and sold by bartenders.

Consequently, women used Fromm's recipe to hand-dip their own condoms.

By the way, the Comstock Act is still in effect. The current and previous Administrations ignored it because Roe v. Wade assured access to abortions, and therefore seemed to nullify Comstock. Now that Roe is gone, Republicans such as Supreme Court Justice Clarence Thomas want to re-impose Comstock. They're unlikely to use it to criminalize the shipping of condoms, of course. The goal is to stop abortions (as opposed to surgical ones) by halting the distribution of drugs used for medical abortions, such as mifepristone.