**Reproducibility**

One of the key factors facilitating the development of new materials in engineering disciplines is the adoption of a comprehensive and reliable set of standards. Such levels of standardisation are difficult to achieve in the context of biological systems, which often have a high degree of uncertainty. This condition does not refer exclusively to the complexity of the biological systems themselves, but to the availability of infrastructures that have the capacity to support the development of standardised practices. Specifically, one of the main limitations to overcome is the conversion of the laboratory scale protocols into much larger and industrial-size equivalents.

### **Automation**

The use of machines and new manufacturing technologies in highly specialised and controlled environments is an important challenge shared by industries ranging from biomedicine, chemistry, and biotechnology to architecture. Weariful and repetitive tasks that are prone to error when done by humans are already being accomplished in many laboratories and industries with robots. This includes tasks such as liquid handling, as well as additive and subtractive manufacturing. The use of machines in environments such as the ones needed to produce mycelium-based materials creates a condition that intrinsically minimises human intervention, ensuring a safe environment during the fabrication process.

### *3.6. Agile In Situ Setup and Applications*

In large part, mass-produced mycelium-based materials that have seen commercial success consist of MBC grown in moulds. This fabrication method relies on a closed, sterile environment. Growing mycelium in situ without a controlled environment has only seen success on a small-scale, while 3D printing has similarly succeeded on a small scale and within a controlled environment. Scaling up in situ applications requires a better understanding of preventing contamination, as well as the development of techniques that do not rely on such a restrictive, closed-off space. Whereas prefabricated MBC can rely on moulds to ensure a closed environmental system, when scaling up there is a need for this controlled environment to be larger than just the mould of one module.

Implementation of new fabrication techniques with mycelium-based materials in a controlled, sterile environment at an architectural scale presents a number of challenges. For example, the use of a robotic arm for mycelium prototyping requires a cleanroom with accurate humidity and temperature control. This constraint is an opportunity to create a walk-in prototyping space able to facilitate the production of large-format prefabricated and highly customised parts. These environments can potentially be located adjacent to the construction site, ultimately reducing costs of transport.

Within this framework, it may be even possible to consider these controlled environments as new construction sites, wherein prefabricated parts and substrates are simply installed and subsequently bound together using the binding capacity of the mycelial network. By approaching the controlled environment as the construction site, it is possible to develop an in situ bio-assembly process in which building parts are naturally bound and mechanically enhanced.

### *3.7. Cross-Disciplinary Research*

The relevance of mycelium-based materials, as demonstrated in this paper, is not limited to their original fields of microbiology and mycology. Thanks to the work of researchers across many disciplines, their relevance has expanded into architecture. These fields are practically unrelated by tradition and in practice. However, the research and development to explore bio-based materials in general have drawn them closer together. While this increases the scope of research and development being done with these materials, it also means that this information does not easily cross over into the other fields. Furthermore, whenever that information does make the jump between disciplines, it can be difficult for an architect, for example, to discern the findings of a microbiologist. Therefore, the cohesive understanding of latest findings and material developments presents its own challenge as many factors prevent the knowledge from being distributed among experts from different industries.

As research on mycelium-based materials continues to exponentially increase year after year, the accessibility of the research also increases. This indicates that the visibility of research increases, and thus the dissemination of information across fields of research will naturally increase. Active efforts to regularly collaborate across different industries can best promote the sharing of findings and development of new technologies. The conscientious integration of the advances from different fields can also further unify the industries and spur new research. In this way, several other previously mentioned challenges in scaling up applications of mycelium-based materials can be addressed, such as the generalisation of how substrates, fungal strains, and environmental conditions affect the growth of mycelium. A further integrated approach can also begin to establish new, open-source practices for goals such as mass-production to expedite the scaling up of mycelium-based materials.
