$fn = 64;

// --- Parameters ---
unit_height_mm = 7;      // Height of a single unit 
units_height = 4;        // 4-unit height as requested
total_height = units_height * unit_height_mm;

inner_flat_to_flat = 35; // Inner width of each hexagonal compartment
wall_thickness = 1.5;    // Thickness of the walls
floor_thickness = 1.5;   // Thickness of the bottom floor

// --- Calculated Values ---
F = inner_flat_to_flat;
W = wall_thickness;
C = F + W;               // Center-to-center distance for exact shared walls

// Radii for the hexagons (corner-to-corner distance)
R_in = F / sqrt(3);
R_out = (F + 2 * W) / sqrt(3);

// Center coordinates for the 3 hexagons forming an equilateral triangle
c1 = [0, C / sqrt(3)];
c2 = [C / 2, -C / (2 * sqrt(3))];
c3 = [-C / 2, -C / (2 * sqrt(3))];

// --- Modules ---
module hex_cylinder(r, h) {
    // Rotated 30 degrees so the flat sides face each other
    rotate([0, 0, 30]) 
        cylinder(r=r, h=h, $fn=6);
}

// --- Main Object ---
difference() {
    // Outer body
    union() {
        translate([c1[0], c1[1], 0]) hex_cylinder(R_out, total_height);
        translate([c2[0], c2[1], 0]) hex_cylinder(R_out, total_height);
        translate([c3[0], c3[1], 0]) hex_cylinder(R_out, total_height);
    }
    
    // Inner compartments (hollowed out)
    union() {
        // Z-shifted for floor, height increased slightly to prevent Z-fighting artifacts
        translate([c1[0], c1[1], floor_thickness]) 
            hex_cylinder(R_in, total_height);
            
        translate([c2[0], c2[1], floor_thickness]) 
            hex_cylinder(R_in, total_height);
            
        translate([c3[0], c3[1], floor_thickness]) 
            hex_cylinder(R_in, total_height);
    }
}