Geng Shuai makes a living from videos of absurd contraptions, including an alarm that goes off if your fly is open

A meat cleaver that doubles as a cell phone case. A holder for a watermelon slice. A metal contraption that makes flicking someone on the forehead more painful.These are just a few of the creations designed and made by China’s “useless inventor.”

Geng Shuai, 34, also ironically called “Edison” by his fans, broadcasts his work from his home studio in a village in Hebei province on a live-streaming app almost every day. With more than 2.5 million fans on the platform, Kuaishou, he is one of China’s latest live-stream celebrities.

Geng is part of an industry that generates as much as $4.7bn in revenue, and one that has few parallels outside of the country. In China, the most popular live streams are not of live events or the feeds of friends, but performances or shows held by strangers. Popular live-streams range from people playing video games, singing karaoke, to studying or farming.

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Unlike Youtube stars, perhaps the closest comparison, China’s live stream celebrities interact with their fans, who make comments, ask questions, and, most importantly, send virtual gifts that can be turned in for cash. Top live-streaming celebrities can make as much as 10mn yuan (about $1.45m) a year.

Geng, who dropped out of school after middle school to go work with his father welding pipes and doing other metal work, started to become popular this autumn after a few local media profiled him. Geng had been building his contraptions and recording videos for more than a year.

“Once after chopping some vegetables, I put the knife to the side and answered a phone call. After hanging up, I put my cell phone on the knife and then it occurred to me. I could make a cell phone case out of a knife. I thought it would be interesting and I wanted to share this with other people. I never thought it would become so popular,” Geng says.

Geng now earns most of his income from donations given online, advertisements, and selling his items online.

His other inventions include a 66-cm long comb made out of iron, a device that pushes food up on a skewer to aid eating street food, or an alarm that goes off if your fly is open. “I like things that are unique. They bring novelty to your life, and these new things in everyday, boring life can make you happy,” he said.

The popularity of live-streaming in the country, and people’s willingness to spend money on a free platform, has been attributed to the sense of community that the videos give to isolated youth, busy young professionals, or the so-called diaosi or self-identified “loser” class of Chinese who feel left behind..

Others say the shows offers unedited entertainment in a country where official channels are so tightly regulated.

In his live-stream, Geng tries to listen to his fans. He asks them what they would like to see him make and their requests are often more extreme than his own ideas: iron pants, underwear, or swimsuits. One asked if he could make a spaceship.

“It’s not only children who are playful,” he says. “Everyone has a childish heart, no matter how old they are.”

Additional reporting by Wang Xueying