$fn=64;

// --- Parameters ---
unit_height = 10;        // Height of a single unit in mm
height_units = 3;        // Total height in units
hole_inradius = 15;      // Inner radius (apothem) of each hex compartment
wall_thickness = 2;      // Thickness of the walls between hexes
floor_thickness = 2;     // Thickness of the solid bottom floor

// --- Calculated Variables ---
total_height = unit_height * height_units;
spacing = 2 * hole_inradius + wall_thickness;

// Calculate outer and inner cylinder radii for 6-sided polygons
// We rotate by 30 degrees later, so the radius is measured to the points
hole_r = hole_inradius / cos(30);
outer_r = (spacing / 2) / cos(30) + 0.05; // +0.05 ensures manifold overlap for the union

// --- Main Model ---
difference() {
    // Outer solid honeycomb structure (19 hexes)
    union() {
        for(q = [-2 : 2], r = [-2 : 2]) {
            // Hexagonal grid condition for a 2-ring cluster (1 + 6 + 12 = 19 hexes)
            if(abs(q + r) <= 2) {
                // Axial to Cartesian coordinate conversion
                translate([spacing * (q + r/2), spacing * sqrt(3)/2 * r, 0])
                    rotate([0, 0, 30])
                        cylinder(r=outer_r, h=total_height, $fn=6);
            }
        }
    }

    // Inner storage compartments to subtract
    for(q = [-2 : 2], r = [-2 : 2]) {
        if(abs(q + r) <= 2) {
            // Shifted up by floor_thickness to leave a solid base
            translate([spacing * (q + r/2), spacing * sqrt(3)/2 * r, floor_thickness])
                rotate([0, 0, 30])
                    // Over-extend height by 1mm to ensure a clean top cutout (no Z-fighting)
                    cylinder(r=hole_r, h=total_height + 1, $fn=6);
        }
    }
}