**4. Conclusions**

universally alike; not servilely alike, but fraternally; not with the sameness of coins cast from one mould, but with the likeness of the members of one family' [22]. The new production techniques, along with parametric design tools, could mimic nature and hand-making also under this respect, creating a spatial experience more nuanced along a continuum of varying shape and materiality. However, as already noted, this becomes a further challenge for the architects, who need to rethink even their own role and tasks in order to make full and best

**Figure 23.** Correa et al., 4D printed adaptive component: when closed (https://tinyurl.com/yd7dy728).

**Figure 24.** Correa et al., 4D printed adaptive component: when open (https://tinyurl.com/yd7dy728).

This case study does not purport all the advanced materiality and scale-free features we are discussing, but is noteworthy as it shows the degree of continuously varying detailing along a shape. 'Digital Grotesque has been designed through an algorithmic procedure called "meshgrammars", which procedure consists of rules that articulate the structure out of a primitive input form, by recursively splitting surfaces. The process allows for highly specific local conditions with complex topologies to be generated. […] The resulting form, consisting of a mesh of 260 million individual facets, has a resolution and level of detail that would be impossible to specify using traditional means, whether drawn by hand or mouse. It provides a glimpse

Example: Digital Grotesque—Hansmeyer, Dillenburger, Zurich, 2013.

of the potentials of additive manufacturing' (**Figure 25**) [23].

use of such opportunities.

66 3D Printing

While additive manufacturing has been around in its main techniques already for some 40+ years now, and cannot be considered an immature technology, it is still undergoing a significant innovation process, often through the hybridization of established base-techniques. Furthermore, in its use—especially within the AEC field—its disruptive potential has yet to be exploited and harvested outside the experimental research or pilot projects.

While waiting for 'the ultimate' technique, some limitations of additive manufacturing can be dealt with through a series of smart strategies. One of these consists in limiting its use to only the parts that need customization, so as to overcome the slower production speed still often associated with AM: very often, it is the nodes that can embed the nonstandard, varying part of the overall geometries, thus allowing for the standardization of all other elements. Another strategy consists in the use of such techniques as an indirect means to support other techniques, as it is the case with 3D printed molds to help create freeform concrete structures. In any case, as it is already the case in some fields like engineering, also within AEC it seems that now additive manufacturing techniques can slowly be adopted not only for rapid prototyping of models and components, or as a mere support technique to other more established techniques, but also to produce functional elements within the final, built structures, or even fully functional entire structures.

The adoption of AM techniques in AEC seems likely to bear some lasting consequences going beyond the 'technical' aspects. In fact, similar to how the invention of press systems changed the role of writers and their professional position, or the recording of sounds created a wholly new environment for musicians, so could additive manufacturing produce a lasting impact on the entire world of AEC, especially as regards the role of the architects and the expressive potentialities opened to them.

On the one hand, it is possible to hypothesize more cost-effective outcomes just by the reduced use of materials and working hours granted by the use of these techniques, as for instance topological optimization, form-finding and other computational design techniques. However, such an approach requires that the architects be aware of the underlying geometrical and physical issues and material properties, both in order to create the final shapes—e.g., as a result of constraint-based design approaches—and in view of 'guaranteeing' safety and durability/resilience.

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The Evolution of 3D Printing in AEC: From Experimental to Consolidated Techniques

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On the other hand, it is now possible for architects to regain a wide degree of autonomy (lost with industrialization) as to the creation of nonstandardized elements and custom 'materials', yet within an industrial mass-customized production process. In other words, while the immediate opportunities opened up by AM techniques seem linked just to faster and cheaper production of possibly unconventional and nonstandardized shapes, the greatest opportunities in AEC could lie in the freedom for architects to explore and imagine new languages and solutions that could be at the same time multiperformative in nature, considering multiple constraints and functions, and spatially inspiring.
