10 years ago, we published a blog on 3D Printing (3DP) when we, like many, believed its full potential might materialise over the following decade in many industries. Through recent work for our clients, we had an opportunity to look at the overall state of the technology again when we investigated its application in two very different areas, namely the food sector and the construction industry (https://www.food.gov.uk/research/emerging-challenges-and-opportunities/3d-printing-technologies-in-the-food-system-for-food-production-and-packaging?print=1).

As was the case a decade ago, 3DP receives still regular media attention, and still there is talk about how the technology will revolutionise the future of design and manufacture of all kinds of products by enabling de-centralised production, new business models and novel products at scale. However, now, as was the case for the past three decades, the anticipated revolutionary potential of 3DP is still very slow in manifesting at any substantial scale in most sectors where some 3DP has taken hold. Yes, the different printing modalities, such as powder jetting, laser sintering, extrusion-based varieties, vat polymerisation, and a few others, as well as software and printers have technically improved over the past decade. And yes, the variety and quality of printable materials and printed products has increased, from tissues printed with live cells to little dragons printed from spinach (to entice children) or cycle bridges from steel or concrete, or even (small) buildings. Application areas such as prototyping and small-edition manufacture of bespoke decorative items and 3D printing of spare parts in the car and consumer goods industries have become more mature and have grown somewhat in these early occupied niche markets. Over the past decade it has also become clear that for the foreseeable future it will be the B2B and 3DP services sectors that will contribute most to the growth of the technology, rather than consumer at-home printing.

However, the same, mostly technical, limitations of 3DP that were identified 10 years ago still persist and appear to keep 3DP on that slow trajectory of market penetration it has been on ever since its inception. And still, considerable expertise and skill are required to 3D-print products with consistent quality. So, what has happened to the ‘revolution’ that 3DP was anticipated to deliver – or, have we just missed it while it was happening?

Sure, most novel technologies must go through the hype cycle and need time to establish dominant designs and implementations, followed by the necessary investments to grow into a significant market that adds enough value to justify further investment for growth. This is particularly true for any hardware-based novel technology, a fact we sometimes forget when becoming used to software-based innovation success stories. Also, history tells us that most ‘revolutionary’ technologies have taken many decades to grow and spread to a significant extent, often with substantial, long-term government support, before they truly transformed industries, business models and societies. And indeed, it appears that such government support to further develop 3DP has over the past decade increased in many parts of the world. Some funding programs to support R&D and scale-up activities for the emerging 3DP ‘industry’ are now in place in the US, EU, and parts of Asia. Hence the perception is that 3DP needs still more help to “really” take off. Possibly over the next decade?

To understand some of the reasons for the slow evolution of 3DP, let’s have a look at two examples we have encountered in our recent work in the food and construction sectors. Although they are vastly different in terms of what is printed, namely edible ingredients at a scale of a few centimetres, and concrete at a scale of several metres, overall, their technological evolution seems to be at a very similar stage at present. In both areas 3DP enthusiasts started to explore the possibilities of 3DP in earnest around 15 years ago.

In the food sector generic printers were initially used to print complex decorative shapes using chocolate or sugar, and a small market for bespoke decorative, edible elements now exists, mainly in the confectionary and fine dining sectors. To cater to these markets, a handful of food printers are now on offer, mainly via B2B services, and a small number of specialist food printing businesses offer services for example for special events or in collaboration with restaurants as part of a dining experience. There was also interest by big food manufacturers to explore the technology, and bespoke, more complex pasta shapes are now offered in small editions by one of the world’s largest pasta makers, Barilla, using 3DP. In both sectors, food and construction, academic R&D has increased rapidly over the past decade, and markedly so over the past five years, and has given rise to a number of startups that are offering products and services in both sectors. Equally, many 3DP businesses have failed in the past decade often due to lack of a viable business model, difficulties to scale, or simply not enough demand for 3D printed ware.

What seems to be a recent trend in the food sector is a shift from using 3DP for the production of complex shapes to applications that create novel or desired textures, hence moving away from the original focus of the technology on 3D shapes. The cultured (lab-grown) meat and plant-based meat sectors are examples, where derivative technologies of 3DP, such as multi-nozzle extrusion printing, are used to improve the texture of meat substitute products. Also generating texturised, printed food for patients with difficulties swallowing regular food is an area that is actively investigated by academic research, and first products have been tested for use in hospitals and care homes. This shows that 3DP can act as an enabling technology in unexpected niche application areas where it then can evolve into new directions.

In the construction sector 3DP was first used to create complex shapes for decorative building elements, such as façade panels or internal wall elements. More recently, the printing of some load-bearing elements has been achieved. For example, the main parts of a cycle bridge in the Netherlands were 3D printed off-site followed by assembly at location(https://3dprintingindustry.com/news/worlds-longest-3d-printed-concrete-pedestrian-bridge-unveiled-in-nijmegen-195951/ ). A pedestrian bridge over a canal in Amsterdam made of 3D printed steel was relocated after a few years in use (https://parametric-architecture.com/mx3d-bridge-removed-after-permit-expires-and-will-be-relocated/?srsltid=AfmBOoqbLZZeEkOUvvTzOzvTaFbIIbN9s1Ddacztj1nDAlghOMbr4-S0 ). Entire small buildings have been printed with up to 3 floors in a umber of countries over the past decade (https://builtin.com/articles/3d-printed-house ). However, 3D printed load-bearing concrete parts still need to be joined together and integrated into the main construction framework of a building using additional construction techniques to achieve required structural integrity and safety standards. 3DP of concrete on building sites might appear at first simple, as only one well understood ‘ingredient’ (concrete) is used. However, the intricacies of optimising the printing process on a construction site are far from trivial. The printing speed, concrete ingredient proportions, the necessary addition of reinforcement structures for tensile strength (such as steel bars and meshes), the drying speed of concrete under various weather conditions and many other factors that vary from one construction site and project to the next, all need to be very well aligned and optimised. Moreover, the simple fact that tensile strength is hard to achieve in a structure that is built up of layers with each inter-layer connection being an area of physical weakness, poses limitations in principle. Hence, the off-site printing under controlled external conditions of (mainly decorative) non-load bearing construction elements is the market segment that is more likely here to stay and grow.

In both sectors, regulators have recently started to watch these emerging 3DP markets more closely.  While 3D printed foods and construction elements are not yet regulated specifically anywhere in the world, lawmakers are currently preparing to develop regulatory frameworks that should set standards and prevent potential harm to consumers through products that might pose risks specifically due to the fact that they were produced via 3DP. These risks can in the case of foods arise from the requirement of complex ingredient mixtures (‘food inks’), including ‘healthy’ vegetable paste, to be highly processed and to contain high levels of additives to achieve printability in the first place. Or certain types of food printers might become potential sources of contaminants when not used and maintained appropriately. 3D printing of concrete is now investigated by regulators and standards certification bodies with regards to the many safety and quality standards that apply in the construction industry to the safe use of concrete (past failures to comply with these have just recently been much in the media, with the RAAC concrete scandal closing schools and hospitals across the UK). Such regulatory initiatives at a mid to late Technology Readiness Level (around TRL 7) can be very helpful to shape and support an emerging technology market by making sure that products are actually viable and safe to use, so that consumers gain trust and buy them. As a result, markets can evolve towards benchmarks and investors can invest in more robust technology, supporting further market growth. Until the positive impact that regulation can make on the 3D printing of food and concrete, however, some more time will pass. Maybe time during which some more of the general technical challenges of 3DP might be fixed?

Persisting challenges

What are these challenges that have made 3DP overall a slowly evolving technology? Our perception of 3DP is often shaped by a vision that appeals so much to our magical thinking, namely, to just press a button and have something, often with a complex shape, materialise effortlessly. It is however the technical fundamentals of the 3DP process itself that bring with them some inherent weaknesses that will almost certainly not change any time soon and hence make sweeping and rapid breakthrough revolutions across industries rather unlikely. These inherent challenges may sound by now almost trivial, but are worth remembering when next time considering a 3DP solution to a problem at scale, or wondering why we are still not printing our next pair of trainers at home:

1. Input materials always need considerable R&D efforts to make sure materials are optimised for both the printing process and the exact specifications of the desired end product. This means, first optimising the materials to a certain printer type so they can be printed at all and then work out exact printer parameters to find the right trade-off between printability and the performance criteria the product needs to fulfil. This also means, that ideally, every material might need its own optimised printer hardware, a trend that has clearly happened. And, thirdly, it means that robust composite products made from more than one material will almost be impossible to produce via a single 3D printing process.
2. Any layer-by-layer deposition method will always have the challenge of creating a site of mechanical weakness and inhomogeneity between layers that will affect mechanical strength and other properties of the product. 
3. Although driven by digitally controlled machines, layer-by-layer deposition methods are ‘serial’ and ‘analogue’ technologies in which a material is deposited one point on the print path after the other (although in a continuous manner). This will always make 3DP a relatively slow technology.
4. The additive nature (point by point and layer by layer) will always impact reproducibility of printed products as even minute fluctuations in the input material, the external environment, or operating conditions can cause irregularities in the final product. Hence, 3DP is still best used in well controlled industrial settings.
5. Given these inherent physical challenges, 3DP will in most contexts face difficulties reaching the economies of scale necessary for economic viability. Hence business models need to factor this in from the start when setting out to offer products, as initial market size and ways of making profits will always be impacted by above limitations.

While we can expect that over the next decade some of these challenges might become reduced somewhat due to incremental technical improvements in some 3DP application areas, they are at the very core of the technical principles that are the foundation of 3DP. Hence, for businesses wanting to set out using the technology, they need to keep these challenges in mind from the start when designing their business models optimised for their respective niche markets. And surely enough, more niche markets will emerge in the future based on improved 3DP technology. In another decade, when we might wonder about the revolutionary breakthroughs that 3DP should have delivered by then, we might find again that 3DP has already become an established technology in some industries – and that the revolution has already happened, without us noticing, one niche market at the time. However, we might still not 3D-print our dinner in the kitchen of our 3D printed home.