## 1 Introduction
Therefore, these tools are most suitable for small-batch production, where their manufacturing cost is significantly lower than that of traditional metal-forming tools. Additionally, the elastic deformation of plastic tools reduces friction during forming, eliminating the need for the surface treatments required for metal tools [1; 18]. Because tooling is typically expensive and initial tool tests are often imperfect due to the complexity of modern parts and sheet materials, 3D-printed tools provide an attractive alternative for rapid prototyping and small-scale production [2; 18]. Although extensive research exists on 3D-printed polymer tools for bending and deep drawing, studies on their use in cutting or punching applications remain scarce [2; 13]. Various studies have examined the feasibility of using 3D-printed tools for sheet metal forming. Conventional metal tools are dominant in the sheet metal bending sector, but unfilled and reinforced plastics are being explored as cost-effective alternatives to replace metal components [2; 19]. Additionally, thermoplastics are recyclable, and polymer tool inserts produced via 3D printing or other rapid manufacturing methods can be quickly replaced. Polymer inserts have also been shown to reduce aesthetic defects in bent sheets. Studies indicate that in air bending, polymer tool inserts achieve comparable process capabilities to those of metal tools [2; 19]. Research into using 3D-printed tool inserts in metal frames for V-bending has shown that springback behavior is comparable to that of all-metal tools. Additionally, using plastic tools improves surface quality due to reduced scratching of the workpiece [2; 19]. When all-plastic tools were tested for V-bending, the final bending angle exhibited lower accuracy due to increased elastic deflection. However, the process showed repeatable performance across different materials [2; 31]. Challenges in using thermoplastics for punching applications include their low compressive strength and variability in the manufacturing process caused by 3D printing parameters. Researchers have identified critical printing parameters, such as infill percentage, wall thickness, extrusion width, and printing temperature. Experiments on deep drawing demonstrated that cups could be successfully formed without visible wear on 3D-printed tools [1; 2]. Furthermore, lubrication was found to be unnecessary for forming heat exchanger plates when using plastic tools, thanks to the plastic's anti-friction properties [2]. FDM tools have also been used for 90\({}^{\circ}\) bending tasks. Despite the low strength of plastic tools, they successfully bent sheets, including steel plates, with tensile strengths of up to 440 MPa. However, enhancing tool stiffness is necessary to improve dimensional accuracy [18]. Experiments on deep drawing with plastic dies revealed that high-pressure conditions caused the tools to deform permanently, making them unsuitable for further use [18]. The environmental issues associated with lubricants in metal forming emphasize the importance of developing lubrication-free processes. Plastic tooling has been shown to prevent sticking, a common issue with steel tooling during extrusion [18]. Research combining PLA dies with steel stamps showed that this approach effectively improved the dimensional accuracy of bent parts for both aluminum and steel sheet metals [9; 32]. A consistent theme across the literature is that 3D printing is well-suited for rapid prototyping and the small-scale production of forming tools [2]. Efforts to enhance the mechanical properties of 3D-printed tools have focused on optimizing parameters such as layer thickness, orientation, and infill structure. The anisotropic nature of FDM parts significantly affects their strength and stiffness, with the stronger/strongest properties aligned along the extrusion direction [33; 34; 35]. Dimensional accuracy, influenced by parameters like extrusion temperature, feed rate, and nozzle diameter, is critical for practical applications.