"It's like a reverse chastity belt," one of the creators, 19-year-old Nadja Björk, told AFP, meaning that the wearer is in control, instead of being controlled.
The military-style buckle has a latch that the wearer has to move through a labyrinth into the correct position in order to unlock the belt.
"You need two hands to open it, so the rapist can't hold you down and open it at the same time. It takes a while to figure it out if you don't know what you're doing," she said.
The product was designed as part of a high school project in entrepreneurship and the girls have already sold 300 of the belts in Sweden, priced at 150 kronor.
Björk and one of her partners now plan to start a business to mass produce the belts and are currently in negotiations with potential partners.
"But I'm not doing this for the money," she said. "I'm really passionate about stopping rape. I think it's terrible."
The Swedish media have in recent months given wide and descriptive coverage to rape attacks, though experts' opinions vary on whether there has been an actual rise in the number of such crimes.