The prepared JSON files are fed back into p5js to generate the extruded letters. Just like the initial Extruded Grid sketch, Extruded Letters generates a grid that transforms as it moves along the Z axis.
As it references the JSON file, the grid on each layer is adapted to the sliced data. Where there exists a part of a letter, it will fill in with lines, while other areas will remain empty. This is performed on a layer by layer basis, starting from the base.