$fn=64;

// --- Parameters ---
pot_diameter = 33.5;    // Citadel paint pots are ~33.5mm
clearance = 1.5;        // Extra clearance for easy insertion
hole_depth = 15;        // Depth of the pot recess
rows = 4;               // Number of stepped rows
cols = 5;               // Number of pots per row
step_height = 25;       // Vertical rise per row
step_depth = 40;        // Depth of each step
wall_thickness = 3;     // Outer and divider wall thickness
base_thickness = 3;     // Minimum thickness under the lowest pot
cutout_width = 20;      // Width of the front viewing cutout

// --- Derived Variables ---
actual_diameter = pot_diameter + clearance;
spacing_x = actual_diameter + wall_thickness;
rack_width = cols * spacing_x + wall_thickness;

// --- Main Assembly ---
difference() {
    // Main stepped body
    union() {
        for (r = [0 : rows - 1]) {
            overlap = (r < rows - 1) ? 0.1 : 0; // Ensure manifold union
            translate([0, r * step_depth, 0])
                cube([
                    rack_width,
                    step_depth + overlap,
                    base_thickness + hole_depth + (r * step_height)
                ]);
        }
    }

    // Subtractions for pots and cutouts
    for (r = [0 : rows - 1]) {
        for (c = [0 : cols - 1]) {
            x_pos = wall_thickness + (actual_diameter / 2) + (c * spacing_x);
            y_pos = (r * step_depth) + (step_depth / 2);
            z_pos = base_thickness + (r * step_height);

            translate([x_pos, y_pos, z_pos]) {
                // Pot recess
                cylinder(h = hole_depth + 1, d = actual_diameter);

                // Front cutout for label visibility and grabbing
                translate([-cutout_width / 2, -step_depth / 2 - 1, 0])
                    cube([cutout_width, step_depth / 2 + 1, hole_depth + 1]);
            }
        }
    }
}