iter-png-1/gpt-5.5 / tier-2-l-bracket

```openscad
$fn = 96;

w = 50;
d = 40;
h = 40;
t = 3;

hole_d = 4.5;
cs_d = 8;
cs_depth = 2;

edge_offset = 10;
eps = 0.05;

hole_x = [
    -w / 2 + edge_offset,
     w / 2 - edge_offset
];

module bracket_body() {
    union() {
        // Horizontal flange: +Y direction, outside face at -Z
        translate([-w / 2, 0, -t])
            cube([w, d, t]);

        // Vertical flange: +Z direction, outside face at -Y
        translate([-w / 2, -t, 0])
            cube([w, t, h]);

        // Solid outside corner to make the bend/manifold
        translate([-w / 2, -t, -t])
            cube([w, t, t]);
    }
}

module horizontal_hole(x, y) {
    // Through hole, normal to horizontal flange
    translate([x, y, -t - eps])
        cylinder(h = t + 2 * eps, d = hole_d);

    // Countersink on outside face (-Z)
    translate([x, y, -t - eps])
        cylinder(h = cs_depth + 2 * eps, r1 = cs_d / 2, r2 = hole_d / 2);
}

module vertical_hole(x, z) {
    // Through hole, normal to vertical flange
    translate([x, -t - eps, z])
        rotate([-90, 0, 0])
            cylinder(h = t + 2 * eps, d = hole_d);

    // Countersink on outside face (-Y)
    translate([x, -t - eps, z])
        rotate([-90, 0, 0])
            cylinder(h = cs_depth + 2 * eps, r1 = cs_d / 2, r2 = hole_d / 2);
}

difference() {
    bracket_body();

    for (x = hole_x) {
        horizontal_hole(x, d / 2);
        vertical_hole(x, h / 2);
    }
}
```