Imagine a world where huge cities could be created with the click of a button.
It might seem like the stuff of science fiction, but that's where 3D-printing technology is headed, according to one Dubai-based start-up.
Cazza has designed a 3D-printing crane dubbed the "Minitank", which the company says can layer up to 2,153 square feet (200 sqm) of concrete per day -- making it more than 50% faster than conventional construction methods.
Automating the construction process, according to Cazza, would not only allow developers to build housing in step with rapid population growth, but is also better for the environment.
The mastermind behind the Minitank is a teenager.
Chris Kelsey, CEO and co-founder of Cazza construction automation company, is just 19 years old, and last year used the money he made by selling his previous start-up, Appsitude, to fund his current project.
As well as hiring a team of engineers experienced in the 3D printing field, Cazza also enlisted structural engineers to assess existing 3D printers in the construction world and identify where those designs could be improved.
The company used this knowledge to design a series of on-site mobile 3D-printers, and began testing prototypes that have informed the final design of the Minitank, which is currently under construction itself.
Kelsey says the biggest barrier to the adoption of the Minitank -- should it work when finally built -- will be public misconception.
"People don't realize how much the 3D-printing world has changed," Kelsey tells CNN. "They think that 3D printing is just (about using) plastic. People assume it won't be structurally sound. That's not what we do."
Over the past 15 years, 3D printing has evolved from a novelty technology for printing small toys to a sophisticated process that has transformed mega-industries from fashion to fine art.
Construction, he says, is a natural progression.
Jack Cheng, an associate professor in the Civil and Environmental Engineering Department at The Hong Kong University of Science and Technology, believes the technology has tremendous potential.
"I think it's real, practical technologically. It's possible to print an entire city but, of course, it will depend on the speed. Concrete is not something -- like plastic -- that's hard immediately when it prints. Concrete takes time to solidify," he says.
Cheng adds that in the United States the military has been exploring the idea of 3D printing cities after disasters, when there is a need to urgently rehouse people.
In 2016, the Dubai government announced its 3D Printing Strategy, which aims to see 25% of buildings in the city constructed using 3D printing technology by 2030.
Last year, Cazza was invited by the Dubai Road and Transport Authority (RTA) to present their technology to those overseeing the initiative, the government confirms.
Once based in the US, Cazza subsequently moved its headquarters in the United Arab Emirates state, which is already home to the world's first functional 3D printed office building, constructed by a robotic arm in 17 days.
Kelsey says Cazza has several projects in the pipeline in Dubai, but will not provide details.
"It wouldn't be skyscrapers right off the bat, but they really want to use our technologies for every aspect of construction," he says.
"Unless there's a random, unique material (required) ... any structure you look at that was conventionally constructed, you can print with our machines."
Just press play
The concept of 3D printing a building was first explored seriously by Professor Behrokh Khoshnevis, director of the Center for Rapid Automated Fabrication Technologies at the University of Southern California.
In 2009, Khoshnevis invented a computer-programmed, concrete-extruding 3D printer, capable of printing a 2,500-square-foot structure in 20 hours.
His invention paved the way for other construction companies, such as Cazza, to experiment with 3D printing.
The premise is surprisingly straight forward, requiring just a few components: the computer software, building material, and, of course, the printer.
For Cazza's process, the architect uploads their blueprint onto the computer system, which sends it to the crane printer. The latter then elegantly spins out layers of concrete in the shape of the design.
"You can't see the layering of the material in our designs," says Kelsey. "The framework of the house is the same quality, if not higher, than the typical concrete home."
Competition in the market
Cazza is not the first company to take inspiration from Khoshnevis, who is currently working with Nasa to explore the feasibility of printing houses on Mars.
Chinese construction firm WinSun, for example, in 2014, 3D printed 10 one-story houses in a single day in Shanghai, while last year DUS architects finished printing a 13-room canal house in Amsterdam.
The innovation behind Cazza's technology is that the Minitank -- should the company succeed in making it operational -- will be able to print on-site. WinSun 3D printed the various parts of each Shanghai house off-site and assembled them on location, while DUS printed on-site but the project took three years.
Cheng says seamless printing on-site is a better method of construction.
"Usually, each piece of the prefabricated components look fine, but when you combine them, the workmanship isn't that good and the connections are not stable. So the safety of some pre-fabricated buildings is a concern."
Location, location, location
Printing on location is not only a faster way of working, but it cuts transportation costs and produces less waste.
"The barrier to companies (printing on-site) so far has been that it's extremely difficult to develop a machine with all of the factors needed," says Kelsey.
"There are many videos online of companies 3D printing concrete structures with their machines, but people don't realize that these machines are not scalable for actual use in construction."
The Minitank's crane-like neck can construct buildings up to three storeys high, and the team has a new machine in the works which they say could 3D-print skyscrapers.
Currently, their primary building material is a cement made from 80% recycled materials, but Kelsey says at least three other types of materials are in development.