###### Abstract
The dynamic displacement of the material structure can be controlled (and to a much greater extent than before) by changing the geometric and material parameters through a combination of techniques for selecting the shapes of individual elements, the way they are connected, and the properties of composite structures [23]. This makes it possible to create stretchable electronics, deformable devices, self-assembled fabrication, etc. [24]. Both the geometry and features of these materials can be printed; hence, it is referred to as 4D printing. Traditionally, one of the greatest difficulties with 3D printing of assistive technology has been the comfort and flexibility of the products, with their low thickness and low weight. Currently proposed 3D-printed solutions solve this group of problems (e.g., through an adaptively selected filling factor), but this is not enough to control the flexibility of the product. Another advantage is the fact that an end product, even with a complex shape, can be printed in one piece (one production run), which ensures, if required, high uniformity and repeatability of the preprogrammed properties over the entire surface. The new material can also be sewn, braided, glued, and welded. Materials with various additives can provide antibacterial, magnetic, or optical properties, and can also be more biodegradable, e.g., made of algae, coffee grounds, or wood. Despite the growing and expanding popularity of 3D-printed chainmails, there is a lack of reviews that present current trends in chainmail modelling methods, techniques, and strategies in the context of predicting their shapes, connections, and properties (including personalised profile modelling) in rehabilitation devices. To date, research on applications of artificial intelligence in exoskeletons (wearable robots) has focused mainly on control systems [25; 26; 27], diagnosis support, and therapy monitoring [28], and much less on optimisation of the shapes of the elements, materials used, or their properties [29; 30]. Meanwhile, a 3D-printed, personalised hand exoskeleton (Figure 1) provides the possibility to solve a number of problems as early as at the stage of construction and adjustment of their properties (shapes, materials), while they may be difficult or impossible to solve at later stages or during the clinical use of the exoskeleton. Undoubtedly, further research is needed regarding the deeper incorporation of sustainability and digital twin paradigms in Industry 4.0 [31; 32]. These areas may also affect the material and management issues of the exoskeleton, as technical control should be incorporated in all stages of the exoskeleton life cycle. The requirements of the MDR (Medical Device Regulation, 2017/745/EU) directive [33] and the ISO 13485 standard [34] should also be taken into account to ensure better life cycle control of devices such as prostheses and orthoses. Recent developments in 3D printing of chainmails for biomedical purposes were discussed in [35; 36]. [PERSON] et al. described chainmails fabricated by selective laser sintering (SLS) 3D printing and subjected to magnetic functionalisation to create a lightweight, 4D-printed activation fabric. Interestingly, postprocessing involved immersing the porous prints in ferrofluid and drying them at high temperature. Magnetically activating fabrics produced in this way may have applications in the production of thin, lightweight, and comfortable wearable assistive devices [35]. [PERSON] et al. proposed chainmail with a bending strength 25 times stiffer under low external pressure (about 93 kilopascals) than in the relaxed position, showing promise as a starting material for lightweight and adaptive fabrics for use in exoskeletons, haptic systems, and reconfigurable medical supports [36]. The shapes and/or properties of 4D-printed objects can change in a controlled manner under the influence of heat (body, ambient), illumination, humidity, and pH level, but also the flow of an electric current and interaction with a magnetic field [37; 38].