$fn=64;

// --- Parameters ---
height_units = 4;           // Number of height units
unit_height = 7;            // Height of a single unit in mm (7mm is common for modular bins)
center_distance = 30;       // Distance between centers of adjacent hexagons
wall_thickness = 1.6;       // Thickness of the compartment walls
floor_thickness = 1.6;      // Thickness of the bottom floor

// --- Calculated Variables ---
total_height = height_units * unit_height;

// Calculate outer and inner circumradii to maintain exactly constant wall thickness
// Formula derives from Inradius = Circumradius * sqrt(3)/2
R_out = (center_distance + wall_thickness) / sqrt(3);
R_in  = (center_distance - wall_thickness) / sqrt(3);

// --- Modules ---
module hex_cluster(r, h) {
    union() {
        // Center hexagon
        cylinder(r=r, h=h, $fn=6);
        
        // 6 Surrounding hexagons
        for(i = [0 : 5]) {
            rotate([0, 0, i * 60])
            translate([center_distance, 0, 0])
            cylinder(r=r, h=h, $fn=6);
        }
    }
}

// --- Main Geometry ---
difference() {
    // Outer solid cluster shell
    hex_cluster(R_out, total_height);
    
    // Hollow out the 7 compartments
    // Translated up by floor_thickness, and made slightly taller to prevent Z-fighting
    translate([0, 0, floor_thickness])
    hex_cluster(R_in, total_height + 1);
}