“It makes drawings in the air, following [real] drawings [which] it scans with photo-cells… Plastic comes out of the end of the drawing arm and hardens as it comes.” So wrote Murray Leinster, an American writer in his 1945 short science fiction story. His prescience captured the essence of what is known today as 3D printing.
A 3D printer uses a nozzle with a rapidly drying, putty-like material to build up a three-dimensional object, layer by layer, under computer control. As a result, complex geometries can be produced, including hollow parts and support structures which might otherwise be challenging to hand build.
Hideo Kodama is generally credited with the first 3D printer for plastic models in the spring of 1980 at a Japanese government research institute in Nagoya in Chūbu. However his research attracted little interest, and his employer declined to support the patent which he had filed.
The first commercial 3D printer later emerged in 1987 from 3D Systems in California, a start-up founded by Chuck Hall. It used filaments of photosensitive resins which were cured by ultraviolet light. These first 3D printers cost of the order of €750,000 at today’s values, accounting for inflation.
Surgery and prosthetics
Rapid prototyping with plastic models are not the only things 3D-printed today but also manufactured components, reconstructive surgery and prosthetics, ornaments and mementos, fashion items and even custom-made shoes.
Larger items can also be 3D-printed. Ma Yihe, a Chinese entrepreneur, founded Winsun in Shanghai in July 2003 to develop 3D-printed architectural components. At the end of 2014, Winsun pioneered a remarkable 10m-high, five-storey apartment block using 3D-printed concrete components. To date, Winsun has been used in more than 400 public building works projects across China.
Winsun 3D prints concrete and glass-fibre composite components in its factory and then assembles the structures onsite. More recently, start-ups have demonstrated printing entire buildings directly in situ. Co-founded by chief executive Jason Ballard in Austin, Texas, in 2016, Icon was in 2018 the first American company given a building permit for a 3D-printed home. Icon uses a computer-controlled 14m-wide, 7.5m gantry frame to hover over the site, continuously extruding a lavacrete polymer concrete layer by layer for both the internal and external walls. Apis Cor in Florida, cofounded by chief executive Nikita Cheniuntai in 2014 uses a single robotic tower instead, with a 360-degree rotatable arm which can reach over the site and continuously squeeze out the concrete composite.
The Icon 2016 Austin house is just under 200sq m in floor area. Apis Cor’s first residence was built in 2017 at 38sq m, and was printed in 24 hours. Both were constructed with fixed-position 3D printers. To work on larger floor areas, Icon’s technology requires the disassembly and reassembly of its gantry. The Apis Cor machine is, however, self-propelled, and so can move itself to new positions on the work site.
For the Dubai municipality, Apis Cor in 2019 built a 9.5m-tall, two-storey, 640sq m demonstration building to verify that the technology works well in the humidity and high-temperature conditions of the Middle East.
Waste minimised
A number of the first 3D-printed houses were proof of concepts, but the first owner-occupied house in the US is 110sq m. It was printed in just 12 hours in 2021 and purchased under the Habitat For Humanity housing programme. The University of Nantes (France) built Europe’s first owner-occupied 3D-printed house in 2017. Germany’s first 3D residence was printed in 2021 by Peri (Germany) and Cobod (Denmark), taking 100 hours to complete.
While 3D printing times are fast compared to manual brick laying, and residual waste is minimised, 3D-printed houses still require manual fit-out of the plumbing and electrical systems. Many use timber roof truss systems, although some use concrete roofs. The actual cost and completion time of a specific build depends on the architectural plans but can be well less than half traditional build methods, with completion in a few weeks.
In the last 18 months, a series of projects have announced 3D-printed community estates. Icon has launched a 3D-printed social housing scheme in El Salvador. Mighty Buildings has a 15-unit complex near Palm Desert in California, albeit with components that were 3D-printed off-site before assembly. In January, Pulaski township in Virginia announced 200 housing units by Alquist 3D (a gantry-based 3D printing system).
The interest in 3D-printed housing is accelerating due to rising labour costs, a desire to reduce wastage and environmental damage, and time to market. Building floor areas and heights are now even more practical than the early small demonstration projects, and some composite materials have reduced carbon emissions compared to standard concrete.
Owner-occupied, 3D-printed housing has become more prevalent. While building codes have yet to fully evolve internationally for 3D-printed concrete structures, there is an opportunity for global leadership in the construction industry.
