# D-Shape

D-Shape is a large 3-dimensional printer that uses a binder-jetting, a layer-by-layer printing process to bind sand with inorganic seawater and magnesium-based binder to create stone-like objects. Invented by Enrico Dini, founder of Monolite UK Ltd, the first model of the D-Shape printer used epoxy resin—commonly used as an adhesive in the construction of skis, cars, and airplanes, as a binder. Dini patented this model in 2006. After experiencing problems with the epoxy, Dini changed the binder to the current magnesium-based one and patented the printer again in September 2008.

## Technical description

The D-Shape 3-D printer sits in a 6 m by 6 m aluminum frame. The frame consists of a square base that moves upwards along four vertical beams during the printing process. Stepper motors on each beam control this movement, allowing precise positioning and holding at specific heights. A printer head, spanning the full 6-meter horizontal length of the base, contains 300 nozzles spaced 20 millimeters apart. An aluminum beam runs perpendicular to the printer head, connecting it to the base.

## Process

Before printing, a 3-D model of the object to be printed must be created using CAD, a software that allows a designer to create 3-D models on a computer. Once the model is finished, the CAD file is sent to the printer head. The printing process begins when a layer of sand, 5 to 10 mm thick, mixed with solid magnesium oxide (MgO), is evenly distributed by the printer head in the area enclosed by the frame. 3-D printing software slices the 3-D model into 2-D layers for printing. Then, starting with the bottom slice, the head moves across the base and deposits an inorganic binding liquid made up of a solution that includes magnesium chloride, at a resolution of 25 DPI (1.0 mm). The binder and sand chemically react to form a sandstone material. It takes about 24 hours for the material to completely solidify. The material resembles, by composition, Sorel cement.
An electric piston moves the printer head perpendicular to the motion to fill gaps and ensure uniform binder application. D-Shape completes each layer with four forward and backward strokes. Stepper motors on the vertical beams adjust the base upwards after a layer is completed. The hollow framework above the printer head is refilled cyclically, distributing new sand into the frame to form the next layer. During the printing process, excess sand supports the solidifying material and can be reused for subsequent printings. The process continues uninterrupted until the desired structure is fully printed.
After the printer is done with this process, the final structure must be extruded from the sand. Workers use shovels to remove the excess sand and reveal the final product. The magnesium oxide in the sand chemically reacts with the binder, forming a microcrystalline mineral-like material. Compared to concrete, which has low resistance to tension and, as a result, needs iron reinforcement, D-Shape's structures have relatively high tension resistance and do not need iron reinforcement. The building process is reported to take a quarter of the time and a third to a half of the cost of building the same structure with traditional means using Portland cement, the material currently used in building construction.

## Awards and achievements
### NYC Waterfront Construction Competition

In the fall of 2012, D-Shape entered into the NYC Waterfront Construction Competition hosted by the New York City Economic Development Corporation (NYCEDC) in which competitors had to create a solution to help strengthen New York City's deteriorating piers and coastline structures. D-Shape's idea called, "Digital Concrete," was to take 3-D scans of each piece of pier or infrastructure and then print a support jacket for each specific piece. D-Shape won first place and received $50,000 for the idea, and estimated that it could save New York City up to $2.9 billion.

### Radiolaria

In 2009, D-Shape printed a large 3-D sculpture, Radiolaria. The sculpture was created by Italian architect Andrea Morgante and inspired by radiolarians, unicellular organisms with intricate mineral skeletons. The original version of the sculpture was a 3 x 3 x 3 m scale model of the full-size Radiolaria that was planned to be put in a roundabout in Pontedera, Italy.

## Recent Developments

Currently, Jake Wake-Walker and Marc Webb are working on a documentary titled The Man Who Prints Houses, about Enrico Dini and his invention.
D-Shape is still in development. It has printed a trullo, but the printer is unable to print larger structures.

### Lunar bases

Because of D-Shape's capabilities, the European Space Agency (ESA) has taken interest in using the printer to build Moon bases using lunar regolith. D-Shape has been successful in printing components for the lunar bases with a simulated regolith and has tested to see how the printer will work in the environment on the Moon.