$fn = 64;

// Parametric Dimensions
length = 80;
width = 60;
height = 50;
wall_thickness = 2;
corner_radius = 5;
rim_overhang = 2;
rim_height = 3;

// Helper module for rounded rectangular prisms
module rounded_box(l, w, h, r) {
    hull() {
        translate([ l/2 - r,  w/2 - r, 0]) cylinder(h=h, r=r);
        translate([-l/2 + r,  w/2 - r, 0]) cylinder(h=h, r=r);
        translate([ l/2 - r, -w/2 + r, 0]) cylinder(h=h, r=r);
        translate([-l/2 + r, -w/2 + r, 0]) cylinder(h=h, r=r);
    }
}

// Main Bin Construction
union() {
    // Main Body
    difference() {
        // Outer Shell
        rounded_box(length, width, height, corner_radius);
        
        // Inner Hollow Cutout
        translate([0, 0, wall_thickness])
            rounded_box(
                length - 2*wall_thickness, 
                width - 2*wall_thickness, 
                height + 1, 
                max(0.1, corner_radius - wall_thickness)
            );
    }

    // Top Rim (Adds structural rigidity for 0.5kg load)
    translate([0, 0, height - rim_height])
    difference() {
        // Outer Rim Extrusion
        rounded_box(
            length + 2*rim_overhang, 
            width + 2*rim_overhang, 
            rim_height, 
            corner_radius + rim_overhang
        );
        
        // Inner Rim Cutout (matches the main hollow cutout)
        translate([0, 0, -1])
            rounded_box(
                length - 2*wall_thickness, 
                width - 2*wall_thickness, 
                rim_height + 2, 
                max(0.1, corner_radius - wall_thickness)
            );
    }
}