*2.1. Equipment and Evaluation Geometries*

The sheet material used in all parts of this study is commercially pure aluminum, EN AW-1050A H14, of 1.0 mm thickness (Sanistål, Aalborg, Denmark). Two forming processes are considered, V-bending and groove pressing. The initial blanks for each process have dimensions of 30 mm × 70 mm and 30 mm × 90 mm, respectively, with the target geometries of the processes shown in Figure 1.

Both forming processes were carried out in an electric press with a maximum capacity of 150 kN. A sub-press, designed for use with interchangeable tool inserts and is shown in Figure 2, is used to ensure proper guidance of the printed forming tools during forming. All experiments were conducted to fixed end positions with a vertical press speed of 3 mm/s.

All forming tools used in this study were printed using a Fused Filament Fabrication (FFF) printer of the Ultimaker 2+ type (Ultimaker, Utrecht, The Netherlands). This printer extrudes a polylactic acid (PLA) filament of Ø2.85 mm through an Ø0.4 mm nozzle. From new, it has an XY-positioning (plane) accuracy of 12.5 µm and a Z-positioning (vertical) accuracy of 5 µm [8]. Using Vat Photopolymerization Additive Manufacturing (VPAM) as a method of producing tools was also investigated. The principle of the method is that liquid resin is selectively cured by a UV light in a layer-by-layer fashion. The printer used

in this case was an Elegoo Mars 2 Pro, which has an XY-positioning (plane) accuracy of 50 µm, and an accuracy of 1 µm along the *Z*-axis (vertical).

**Figure 1.** Target geometries with dimensions in mm: (**a**) sheet formed by V-bending; (**b**) sheet formed by groove pressing.

**Figure 2.** Sub-press with tools mounted for (**a**) V-bending and (**b**) groove pressing.
