How to remove internal part of a hex grid
I ended up finding a reasonable solution myself:



Basically, I diffed two identical, non-hollow geometries, in which the first one had the cells larger than they needed to be (so overlapping with others), and the second one had them exactly of the right dimension:

difference() {
  base_geometry(range, angle, infill, extra_padding = 2);
  base_geometry(range, angle, infill, extra_padding = 0);
}


This way the only portion of the solid remaining was the extra_padding on the outer edges of the geometry.