Malian workers haul out a boat they use to carry sand collected from the river bed during a routine maintenance on October 7, 2018, in the port of Bamako. Increasing construction in the Malian capital has boosted the demand for bricks made out of high-quality Niger River sand. (Photo by Michele Cattani/AFP Photo)

A girl paddles on her stand-up board on the waters of Guanabara bay at Bica beach in Rio de Janeiro Brazil, January 10, 2016. Few features capture the beauty, or the problems, of one of the world's most dramatic urban landscapes like Guanabara Bay - the finger-like inlet that forms the shoreline and harbor for Rio de Janeiro. The bay, which carves into southeast Brazil from the Atlantic Ocean, literally gave Rio its name when Portuguese mariners mistook it for a “rio”, or “river”. Four centuries later, the bay is preparing to welcome another sort of seafarer – Olympic sailors, who will navigate the bay when the 2016 Rio Olympics kick off in August. (Photo by Ricardo Moraes/Reuters)

In this photo taken on March 16, 2019, 13-year-old Reymark Cavesirano collects left over herring onboard a fishing boat anchored at the mouth of Manila Bay off Navotas City in suburban Manila. Cavesirano, a grade five student, paddles to the anchored fishing boats and helps crew clean their nets, and in exchange collects leftover herring still tangled in the nets. Across the Philippines, there are 5 million child labourers, aged between five and 17, many of them working in dangerous conditions. About 22 million people – a fifth of the population – live below the national poverty line. (Photo by Ted Aljibe/AFP Photo)

In this photo taken on Saturday, May 16, 2015, Snoek fish with salt on them after they were cleaned in Lambert's Bay, South Africa. The boats line up along the jetty, bobbing in the cold south Atlantic waters, bringing in the day's catch in the early afternoon. The long silver snoek fish is one of South Africa's traditional foods, and a main source of income for the town of Lambert's Bay. (Photo by Schalk van Zuydam/AP Photo)

With the city of Miami skyline behind it a grand piano is seen on a sandbar in Biscayne Bay on January 26, 2011 in Miami, Florida. It's unknown how or why the heavy musical instrument was on the sandbar but some were speculating it was part of a music video production. The piano was charred from being burned. (Photo by Joe Raedle/Getty Images)

These stunning sand sculptures are being used to encourage youngsters to explore their surroundings and play in the dirt. (Photo by OMO Lowe)

It has taken 3,000 hours and 34 years to make – but the results are incredible. Artist Scott Weaver has created a huge but incredibly detailed model of San Francisco using 100,000 toothpicks. The work entitled Rolling Through the Bay also doubles as a marble run. Ping pong balls dropped on several ramps at the top of the model follow several “tours” through the city. They pass matchstick replicas of sights such as Alcatraz, Fisherman's Wharf, the Golden Gate Bridge and the city's trademark terraced houses on steep hills.