The SCAD file for the s_press_mould is for woodworkers who want to make short, s-shaped laminations using either very thin slices of wood or, as illustrated here, slices of veneer.  Adjustments of parameters in the OpenSCAD source let you adjust the radius and length of the curved portions, the length of straight extensions beyond the curves, and the width and thickness of the lamination.  You can also adjust the overall size of the block to help centre the s-shaped form.  In my own applications I have used PLA with 30% infill which stood up to firm clamping with two Bessey F-style clamps.