## 2 Materials and Methods
### Investigation of Material Selection for the Plastic Enclosure of the Measurement Strap  
Materials used for constructing the enclosures of the armlet with wet circuit measurements and conducting the tests were selected from various types of plastics, including ABS, Z-ASA, PC/ABS, Z-ULTRAT, Z-HIPS, and PVC. Below, we present the characteristics provided by the manufacturers for each material:  
ABS Material  
As part of the study, the first set of armlets with wet circuit measurement was made from ABS material. Initially, the enclosures for the straps were designed and then 3D printed. Z-ASA Pro (Acrylonitrile Styrene Acryl) is a stable thermoplastic material for 3D printing, resistant to changing weather conditions and UV radiation. Z-ASA Pro ensures that models will not change color or physical properties even after extensive testing in open spaces. Its high-temperature resistance allows for testing models under direct sunlight without the risk of deformation or discoloration. Z-ASA Pro is also suitable for precise 3D printing of large models due to its low shrinkage and deformation levels. It is obtained through the copolymerization of SAN (Styrene Acrylonitrile) with acrylic rubber. PC/ABS is a blend of polycarbonate (PC) and ABS (Acrylonitrile Butadiene Styrene) fibers. The filament is impact-resistant, UV-resistant, and can withstand high temperatures. Z-PCABS is also resistant to various chemicals, including salts, acids, and bases. The material is ideal for prototyping, printing specialized tools, and manufacturing final parts. Objects 3D printed with Z-PCABS remain fully functional and durable even with prolonged use. The filament is also suitable for creating enclosures, tools, structural components, and automotive parts exposed to impact and various chemical substances. Depending on the composition, it combines the properties of both materials. It exhibits good hardness, impact resistance (comparable to PC), resistance to creep under static loads, higher thermal resistance than ABS, good electrical insulation, and low moisture absorption. Below are the selected parameters of the PC/ABS material. Z-ULTRAT is a 3D printing filament based on ABS (Acrylonitrile Butadiene Styrene) designed to provide excellent strength and model quality (Figure S1). It is ideal for applications where high quality is a priority, such as functional prototyping, final parts, or consumer products. Z-ULTRAT is resistant to high temperatures and impact, and its exceptional hardness allows for demanding tests. It is available in seven colors. The filament is easily processed chemically and mechanically. This material enables the printing of models with physical properties similar to those produced using injection molds, thereby reducing the costs of low-volume production while maintaining high quality. It is obtained through the polymerization of butadiene and the copolymerization of acrylonitrile with styrene, with simultaneous grafting of the resulting copolymer onto polybutadiene. It is an amorphous material with high impact resistance, hardness, and scratch resistance. However, it lacks resistance to light and UV radiation. It exhibits good insulation properties and satisfactory resistance to alkaline substances, diluted acids, aliphatic hydrocarbons, oils, and fats. However, it is not resistant to acids, esters, and ketones. ABS has a wide processing window, especially regarding temperature profiles. Drying of the material is required for applications with high aesthetic surface requirements. Below are the selected parameters of the ULTRAT material with the following composition: ABS (Acrylonitrile Butadiene Styrene copolymer)--90-100%, PC (polycarbonate)--0-3%. Z-HIPS (High Impact Polystyrene) is perfect for printing large models. Its strength allows for mechanical and functional testing. Compared to other polystyrene materials, Z-HIPS has been modified to give models a unique semi-matte finish. The surface quality of prints from this material is comparable to that of components produced using injection molds.