$fn=64;

// --- Parameters ---
arm_length = 100;      // Length of both horizontal and vertical arms
bracket_width = 25;    // Width of the bracket
thickness = 6;         // Thickness of the main arms
rib_thickness = 4;     // Thickness of the side support ribs
hole_dia = 4.5;        // Diameter of the mounting holes (fits #8/#10 screws)
cs_dia = 8.5;          // Countersink outer diameter

module shelf_bracket() {
    difference() {
        union() {
            // Vertical arm (mounts to wall)
            translate([0, 0, -arm_length + thickness]) 
                cube([thickness, bracket_width, arm_length]);
            
            // Horizontal arm (supports shelf)
            cube([arm_length, bracket_width, thickness]);
            
            // Left support rib (U-channel design for strength)
            hull() {
                translate([thickness, 0, 0]) 
                    cube([0.1, rib_thickness, 0.1]);
                translate([arm_length - 5, 0, 0]) 
                    cube([5, rib_thickness, 0.1]);
                translate([thickness, 0, -arm_length + thickness]) 
                    cube([0.1, rib_thickness, 5]);
            }
            
            // Right support rib
            hull() {
                translate([thickness, bracket_width - rib_thickness, 0]) 
                    cube([0.1, rib_thickness, 0.1]);
                translate([arm_length - 5, bracket_width - rib_thickness, 0]) 
                    cube([5, rib_thickness, 0.1]);
                translate([thickness, bracket_width - rib_thickness, -arm_length + thickness]) 
                    cube([0.1, rib_thickness, 5]);
            }
        }
        
        // --- Mounting holes ---
        
        // Vertical arm holes (Wall side)
        // Lower hole
        translate([-1, bracket_width/2, -arm_length + 20]) 
            rotate([0, 90, 0]) cylinder(h=thickness+2, d=hole_dia);
        translate([thickness - 3, bracket_width/2, -arm_length + 20]) 
            rotate([0, 90, 0]) cylinder(h=3.1, d1=hole_dia, d2=cs_dia);
            
        // Upper hole
        translate([-1, bracket_width/2, -20]) 
            rotate([0, 90, 0]) cylinder(h=thickness+2, d=hole_dia);
        translate([thickness - 3, bracket_width/2, -20]) 
            rotate([0, 90, 0]) cylinder(h=3.1, d1=hole_dia, d2=cs_dia);

        // Horizontal arm holes (Shelf side)
        // Inner hole
        translate([25, bracket_width/2, -1]) 
            cylinder(h=thickness+2, d=hole_dia);
        translate([25, bracket_width/2, -0.1]) 
            cylinder(h=3.1, d1=cs_dia, d2=hole_dia);
            
        // Outer hole
        translate([arm_length - 20, bracket_width/2, -1]) 
            cylinder(h=thickness+2, d=hole_dia);
        translate([arm_length - 20, bracket_width/2, -0.1]) 
            cylinder(h=3.1, d1=cs_dia, d2=hole_dia);
    }
}

// Render the bracket
shelf_bracket();