$fn = 128;

// Parameters
tolerance = 0.6;          // Extra diameter for easy bit insertion
tier_depth = 24;          // Depth of each tier
tier1_h = 20;             // Height of the front tier
tier2_h = 35;             // Height of the back tier
width = 160;              // Total width of the holder

// Drill bit sizes in mm
front_bits = [1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5];
back_bits = [6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10];

difference() {
    // Main Body
    union() {
        // Front tier (added 0.1mm depth to ensure manifold union)
        cube([width, tier_depth + 0.1, tier1_h]);
        // Back tier
        translate([0, tier_depth, 0]) 
            cube([width, tier_depth, tier2_h]);
    }

    // Front Row (1mm to 5.5mm)
    for (i = [0 : len(front_bits) - 1]) {
        // Calculate hole depth based on bit size
        depth = 10 + front_bits[i] * 1.5;
        
        // Drill bit hole
        translate([(i + 0.5) * (width / len(front_bits)), tier_depth * 0.65, tier1_h - depth])
            cylinder(h = depth + 10, d = front_bits[i] + tolerance);
        
        // Size label (Debossed)
        translate([(i + 0.5) * (width / len(front_bits)), tier_depth * 0.22, tier1_h - 1])
            linear_extrude(2)
            text(str(front_bits[i]), size = 4.5, halign = "center", valign = "center", font = "Arial:style=Bold");
    }

    // Back Row (6mm to 10mm)
    for (i = [0 : len(back_bits) - 1]) {
        // Calculate hole depth based on bit size
        depth = 15 + back_bits[i] * 1.2;
        
        // Drill bit hole
        translate([(i + 0.5) * (width / len(back_bits)), tier_depth * 1.65, tier2_h - depth])
            cylinder(h = depth + 10, d = back_bits[i] + tolerance);
        
        // Size label (Debossed)
        translate([(i + 0.5) * (width / len(back_bits)), tier_depth * 1.22, tier2_h - 1])
            linear_extrude(2)
            text(str(back_bits[i]), size = 5.5, halign = "center", valign = "center", font = "Arial:style=Bold");
    }
}