"Behind the small boxes are people's respect for their millennia-long history and civilization. It also shows that the development of cultural products has entered into the phase of providing a joyful experience and involvement," Yang adds.

Henan Museum in Zhengzhou, Henan province, was the first in China to produce the dig box in 2019. It has made various series of dig boxes in the past few years. The sales of its dig boxes have reached up to more than 30 million yuan ($4.2 million), according to Wan Jie, Party chief of Henan Museum.

Wan attributes the good revenue to young people's love for this museum merchandise. More than 60 percent of their visitors are under the age of 35 and more than half of these young people are female.

Wan estimates that there will be more than 1.8 million visitors this year, under a daily cap of 10,000.Additionally, buying museum products is popular among young people.

"Young people love to buy items, especially through our online store. Some never have the chance to come to our museum, but they still buy our products," says Wan.

On one hand, a popular cultural product offers a chance for people to learn stories of those relics and treasures housed at the museum, and on the other, it has to be practical or can be used in daily life.

The most popular item in Henan Museum now is a series of jade-shaped lollipops. They are designed on a pair of jade pieces of a male face and a female face, which were unearthed in a couple's tomb from the Spring and Autumn Period (770-476 BC).

To attract young people, the museum has set up a consultant team made up by various professionals to discuss their proposals for potential museum products. They have also collected data from the market to analyze their consumers' favorites.