$fn=64;

// --- Parameters ---
holder_width = 120;
front_depth = 30;
back_depth = 30;
front_height = 15;
back_height = 30;

// Hex bit settings (sized for standard 1/4" / 6.35mm bits)
hex_hole_dia = 7.2;
hex_hole_depth = 11;
hex_holes_per_row = 10;

// Small tool settings (for screwdrivers, tweezers, etc.)
tool_hole_dia = 12.5;
tool_hole_depth = 25;
tool_holes_per_row = 6;

// --- Geometry ---
difference() {
    // Main stepped body
    union() {
        // Base spanning the whole depth
        cube([holder_width, front_depth + back_depth, front_height]);
        // Raised back tier
        translate([0, front_depth, 0])
            cube([holder_width, back_depth, back_height]);
    }

    // Front row: Hex bits
    for (i = [0 : hex_holes_per_row - 1]) {
        translate([
            (holder_width / hex_holes_per_row) * (i + 0.5),
            front_depth * 0.30,
            front_height - hex_hole_depth
        ])
        cylinder(h = hex_hole_depth + 1, d = hex_hole_dia);
    }

    // Middle row: Hex bits
    for (i = [0 : hex_holes_per_row - 1]) {
        translate([
            (holder_width / hex_holes_per_row) * (i + 0.5),
            front_depth * 0.75,
            front_height - hex_hole_depth
        ])
        cylinder(h = hex_hole_depth + 1, d = hex_hole_dia);
    }

    // Back row: Small tools
    for (i = [0 : tool_holes_per_row - 1]) {
        translate([
            (holder_width / tool_holes_per_row) * (i + 0.5),
            front_depth + (back_depth * 0.5),
            back_height - tool_hole_depth
        ])
        cylinder(h = tool_hole_depth + 1, d = tool_hole_dia);
    }
}