Cai Honghao's hammers and shaping tools. [Photo by Gao Shan/Xinhua]

Depending on the complexity, a work can take a week to several months, with the prices up to tens of thousands yuan.

Leather crafters around the world mostly use "vegetable leather", from Japan's Tochigi Prefecture. This leather is soaked in vegetable tannic acid for over a month before crafting.

"This kind of leather is absorbent and easy to shape," Cai says. "Over time, it darkens and takes on a fine gloss." He often buys the leather direct from Japan. Each whole piece costs around 3,000 yuan.

He shows his work on Taobao, one of China's biggest online markets, but his customers prefer to visit his studio to order customized designs.

He disdains mass production: "That means changing artworks into products."

Cai also teaches five-day workshops for a fee of 6,000 yuan. College students, professors and white collar workers are among those keen to learn the basic skills.

Cai himself learned from internet videos and Japanese books. He has taken on a 25-year-old woman as an apprentice.