# Additive Manufacturing in Bespoke Interactive Devices--A Thematic Analysis
## 4 Discussion
Relationship between Additive Manufacturing and Generative Design Algorithms  
Automated digital workflows are an essential tool to enable designers to design for AM in interactive devices. Their superior virtual placement analysis and time and cost savings facilitate design concept optimisation. The complex relationships between process parameters, functional characteristics, and material properties can easily be modelled by generative design algorithms. This process is challenging, as the design requirements can be conflicting in nature [40], and can lead to manufacturability issues during production [39; 43; 44]. One of the main capabilities of AM is the generation of complex geometrical surfaces. Topological optimisation was highlighted as being commonly used to feasibly integrate these geometries into the design of bespoke devices [33]. The workshops and literature noted that design knowledge for traditional manufacturing technologies is not suited to the design of additive manufactured products [32]. Furthermore, adapting existing products for AM is difficult, due to the specific AM constraints. To support designers in designing for AM, automated workflows can be utilised. These design support systems need to be suited for AM design, as traditional manufacturing-specific systems cannot be effectively applied [30; 31]. It has been shown in both research [32] and workshops that designers should be more effectively guided when designing additive manufactured products. Accessible design tools are required [29], as there is a significant skills gap in the production of additive manufactured interactive devices. The lack of AM knowledge and tools was evident in both the literature and the workshops' themes. Workshop 2.2 indicated that a cohesive AM design tool is required by designers. However, [PERSON] et al. (2015) found that a variety of DFAM tools should be available to designers, since they have their individual preferences and experiences [27]. Furthermore, the lack of standardisation impedes training and education development. A successful transition to AM requires stakeholders to be knowledgeable on modelling software. Relationship between User-Centred Design and Generative Design Algorithms  
Bespoke devices are characterised by highly specific dimensional schemas, since they are required to conform to the patient's body. Generative design workflows can guide the designer in this process, by utilising raw data inputs to develop bespoke device formations. It was found that human-machine collaboration makes a UCD concept more attainable [40]. The main attribute of the algorithmic design is in the parameterisation of user requirements, through the analysis of the human body and biomechanics. The 3D models generated by design algorithms allow the user to evaluate the design concept in real time, prior to production. This will reduce the amount of patient visitations during the later stages, and allows the interactive device to be aligned with existing implants. Workshop 1.2 noted that machine learning is typically used to support the designer when balancing user requirements and post-processing constraints. Relationship between Measurement Devices for Data Acquisition and Virtual Reality, Augmented Reality, and Haptics  
Raw data acquired from scanning devices is used to generate 3D models of the interactive device, in order to conform to the geometrical constraints of the end-user's body. For the user to be fully immersed in virtual and augmented realities, sensory integration is required through tracking devices. From the workshops, it was concluded that, ideally, an effective tracking system would be accurate, reliable, capable of measuring absolute position and orientation, not affected by the environment, have fast processing times, and not be subjected to drift. However, there is no system that is capable of fulfilling these functions; therefore, a hybrid system would ideally be employed to benefit from the advantages of the individual tracking systems.