bare-think-off/gemini-3.5-flash / tier-2-l-bracket

```openscad
// L-bracket parameters
width = 50;       // Width of the bracket (X direction)
depth = 40;       // Depth of the horizontal flange (Y direction)
height = 40;      // Height of the vertical flange (Z direction)
thickness = 3;   // Thickness of the bracket

// Screw hole parameters (M4 countersunk)
d_hole = 4.5;     // Through hole diameter
d_sink = 8.0;     // Countersink maximum diameter
h_sink = 2.0;     // Countersink depth
hole_offset = 10; // Distance from the edge

$fn = 60;         // Smoothness of circles

module countersunk_hole() {
    // Generates a countersunk hole along the Z-axis
    // The head of the screw is on the Z+ side, pointing downwards (Z-)
    union() {
        // Through hole (extended to ensure clean cut)
        translate([0, 0, -20])
            cylinder(d = d_hole, h = 40);
        
        // Countersink cone
        translate([0, 0, -0.01])
            cylinder(d1 = d_hole, d2 = d_sink, h = h_sink + 0.01);
        
        // Excess upper cylinder for clean subtraction
        translate([0, 0, h_sink])
            cylinder(d = d_sink, h = 10);
    }
}

difference() {
    // 1. Bracket Base Shape (with inner corner at origin [0,0,0])
    union() {
        // Horizontal flange (Y+ direction)
        // Outside is at Z = -thickness
        translate([-width/2, 0, -thickness])
            cube([width, depth, thickness]);
        
        // Vertical flange (Z+ direction)
        // Outside is at Y = -thickness
        translate([-width/2, -thickness, 0])
            cube([width, thickness, height]);
    }

    // 2. Holes on the Horizontal Flange
    // Outside surface is at Z = -thickness. Screw enters from Z- (outside) towards Z+ (inside).
    // We rotate the hole 180 degrees around X-axis so the head is on the Z- side.
    translate([-(width/2 - hole_offset), depth - hole_offset, -thickness])
        rotate([180, 0, 0])
            countersunk_hole();

    translate([width/2 - hole_offset, depth - hole_offset, -thickness])
        rotate([180, 0, 0])
            countersunk_hole();

    // 3. Holes on the Vertical Flange
    // Outside surface is at Y = -thickness. Screw enters from Y- (outside) towards Y+ (inside).
    // We rotate the hole -90 degrees around X-axis so the head is on the Y- side.
    translate([-(width/2 - hole_offset), -thickness, height - hole_offset])
        rotate([-90, 0, 0])
            countersunk_hole();

    translate([width/2 - hole_offset, -thickness, height - hole_offset])
        rotate([-90, 0, 0])
            countersunk_hole();
}
```