They show off their snakes in their Vilakazi Street home, where tourists and local schoolchildren have become regulars.
Mngomezulu said many have since overcome their fear of reptiles, which she described as harmless if handled with care. She urged people not to think of snakes as a menace.
"People are killing snakes every day," Mngomezulu said.
"That's not right."
Her smallest snake, the corn snake, measures 1.2 metres. The Burmese python is three metres long and, at 30 kilograms, is her heaviest snake.
Mngomezulu said her goal is to expand her snake show beyond Soweto.
She is awaiting a permit that would allow her to take the snakes to non-residential areas and hopes money raised can help her to buy more snakes and get formal training from a recognised association. She is registered with the West Rand Herpetological Association, a local club for reptile lovers.
Andre Lourens, the association's chairman, said Mngomezulu's show has been instrumental in dispelling the false notion that all snakes are dangerous.
"They are no more dangerous than any dogs running down the streets, if you take into consideration the amount of dog bites here in South Africa or number of people hit by lightning," Lourens said.
Duma is saving money for university, where she plans to study zoology or psychology.
She said she hopes her experience interacting with the reptiles and educating people about them can lead to a long-term career working with animals.
- AAP