The best-known additive process in digital fabrication is rapid prototyping, which facilitates the quick production of objects from a range of materials depending on factors of time, cost and application. ‘Rapid prototyping’ is often mistakenly used as shorthand for a specific type of additive fabrication, but is a generic term within which a family of different methods are related. The commonality of the various processes lies in the gradual build-up of incremental two-dimensional layers of material to produce a three-dimensional object. The first commercially available rapid-prototyping technique was Stereolithography in the late 1980s. Stereolithography, often abbreviated to SLA, uses liquid polymers that change state and solidify when laser light is traced across them. Each layer is ‘drawn’ by the laser across a tank of lightsensitive liquid polymer, resulting in a solid cross-section of material in relation to the laser’s motion and outline. Once a layer has been made, a small platform inside the machine lowers it beneath the surface of the liquid and this process is repeated until all the necessary layers have been drawn and stacked together, thereby producing the final form. This object is then treated to remove any excess liquid and provide a more robust product. The process of 3D printing is perhaps the most commonly known type of rapid prototyping, as it is frequently referred to under its parent term. In this digital fabrication method, layers of starch or ceramic powder are bonded to make objects. Although the models and components thus manufactured may be cleaned and sealed with an agent to improve their durability, they remain comparatively fragile and their surfaces have a tendency to granulate when handled. More substantial physical results are possible using additive fabrication processes, but 3D printing currently appears the most popular. Laminated Object Manufacturing (LOM) employs sheet material, usually paper or plastic, which is laser cut and then laminated together to form physical artefacts. The process of Fused Deposition Modelling (FDM) fabricates objects by melting a plastic filament that subsequently solidifies as a result of cooling, to make layer upon layer of material to form objects. In a similar manner, the Multi-Jet Manufacture (MJM) technique utilizes a modified printing head to ‘draw’ with thin layers of melted thermoplastic wax, again gradually forming the object in a cumulative process. Selective Laser Sintering (SLS) adopts a parallel approach to the previous two methods, but because of the choice of material – in this case, metal powder – it requires a laser to melt it and develop the thin layers from this.
In their Villa Rotterdam project, ZUS explored the tension between public and private spaces through a complex assembly of interlocking and nested spherical grids. To communicate their design ideas, a model was fabricated using laser cutting and selective laser sintering.
Detail close-up through the spherical grids.
The work of sixteen*(makers) has long engaged with digital technologies as an integral part of their design research and practice – as exemplified by this rapid-prototyped component for the project STAC. The sectional CAD drawings (left) illustrate the data used by stereolithography to build the complex three-dimensional object (right).
Images of a rapid-prototyped model for Paul Broadbent’s Bartlett diploma design thesis, Click-To-Play. The adaptive nature of the project, which related to notions of flux and reordering, produced a design that embraces fluid and ephemeral elements alongside more static ones.
Rogers Stirk Harbour + Partners use rapid-prototyping technology at various scales as a mode of design inquiry. This concept sketch and 3D print of the roof structure for the Santa Maria del Pianto metro station, Naples, represent stages in the design process that ‘bookend’ the evolutionary, algorithmic design as shown on page 60. The model enables the physicality and shading of the roof lattice to be further appreciated.
Similarly, in order to communicate and test the design for the Leadenhall Building, rapid-prototyping techniques, in this case SLS (selective laser sintering) were employed to fabricate 1:50-scale 3D prints of various iterations of the node points in the complex geometry of the external structure. This allowed architectural assessment of these geometries, and eased communication in the design team.
To date, the most significant limitation of rapid-prototyping processes has been the size of objects they are able to fabricate. This factor, further nuanced by the considerable expense of additive fabrication machines along with the relatively long time required to make the objects, has led to a reasonably narrow use in architecture. Their greatest application is typically during the design process, in which they allow the designer to examine complex and curvilinear geometries in physical formations rather than digital ones. Rapid prototyping is also used to fabricate components, which provide prototypical uses for replication via further processes such as moulding and casting. More recently, the process of contour crafting has seen designers, architects and engineers experiment with an additive method similar to FDM but using a fast-setting, compound material similar to concrete to produce full-sized rather than scaled layers. This last-named development is still in its infancy, but may lead to revolutionary changes in the way we make buildings if we are able to ‘print’ them from digital information.
In many respects, physical prototypes exhibit a clarity and legibility that few forms of visual representation can attain. Realized by plastic techniques, the virtue of the prototype lies in its interactivity and the subsequent critical response this initiates.
‘Prototyping’ design ideas. The complexity, relative ease and economic cost of rapid prototyping has allowed practitioners to use its techniques throughout the design process rather than simply to produce final models. This is much more synchronous with the process’s application in other industries – typically, an iterative loop oscillating between design, prototype, revision and development toward a solution. For her Scared Womanhood diploma design thesis, Joanna Szulda used 3D printing to fabricate a final sectional model, shown here in relation to a digital render of the scheme. However, the digital production method was also used to generate explorative tools (middle right) as part of her design development and also to evaluate spaces and components in more detail, as illustrated in the 1:25-scale model (middle left).
Rapid prototyping enables designers to produce complex geometries quickly and relatively economically. Through the interplay between scripting software and 3D printing, this speculative design by Archibureau/ Patrick Drewello evolves a creative dialogue between digital and analogue modes of production.
Digital fabrication techniques have evolved significantly in their relatively short history; perhaps most exciting is the affordability of a number of these technologies and their potential implementation for architects and designers. The RepRap machine illustrated here was created by Dr Adrian Bowyer, a senior lecturer in mechanical engineering at the University of Bath, UK, in 2005. In stark contrast to even low-end commercial rapid- prototyping machines, RepRap has produced a 3D prototyping machine and accompanying free software that are economically viable for students and professionals alike. RepRap uses a variant of fused deposition modelling (FDM) technology, capable of printing plastic objects. Since many parts of the machine are made from plastic and it can print those parts, RepRap is a self-replicating machine – one that anyone can build given time and materials. For more information on how to build your own 3D printer see: http://reprap.org
Case study Printing full-size architectural design
Shiro Studio/D-Shape – Radiolaria Pavilion, Pontedera, Italy, 2008–11.
One of the most significant limitations for 3D printing lies in the maximum dimensions at which a machine can prototype objects. The ambition to ‘print’ a full-size building has driven the Italian engineer Enrico Dini to develop his d-shape technology and company. As with commercially available rapid-prototyping equipment, CAD drawings are translated by the d-shape into 3D layering. The machine deposits and binds layers 5–10mm deep, allowing building designs to be realized to minute tolerances.
A AND B The prototype machinery enables 1:1 sandstone buildings to be fabricated, using a stereolithography process that combines sand and an inorganic binder. The machine comprises a rigid 6m x 6m plan that lifts along four columns which may be extended, by adding parts, up to 12m in length.
C Andrea Morgante, founder of Shiro Studio, has collaborated with d-shape on the Radiolaria Pavilion, a complex, free-form structure produced using the world’s largest 3D printer. The prototype shown here is scaled at 1:4 to evaluate the technology and design.
D The Radiolaria Pavilion aimed to define a complex, self-supporting structure that could demonstrate and test this pioneering construction technique. Measuring 3m x 3m x 3m, the structure represents a scale model of the final pavilion, to be 10m high and built in Pontedera, Italy.
