$fn = 64;

// --- Parameters ---
roll_diameter = 36;
roll_length = 65;
wall_thickness = 2.5;
slot_width = 12;
slot_length = 40;
cap_overlap = 12;
tolerance = 0.2;

// --- Calculated ---
outer_diameter = roll_diameter + 2 * wall_thickness;
body_height = roll_length + wall_thickness;

// --- Layout ---
translate([-outer_diameter/2 - 5, 0, 0]) 
    dispenser_body();

translate([outer_diameter/2 + 5, 0, 0]) 
    dispenser_cap();

// --- Modules ---
module dispenser_body() {
    difference() {
        // Main body
        cylinder(d=outer_diameter, h=body_height);
        
        // Inner cavity
        translate([0, 0, wall_thickness])
            cylinder(d=roll_diameter, h=roll_length + 1);
            
        // Chamfer inner top edge for easier cap insertion
        translate([0, 0, body_height - 1])
            cylinder(d1=roll_diameter, d2=roll_diameter + 2, h=1.1);
            
        // Snap fit groove
        translate([0, 0, body_height - 4])
            rotate_extrude()
            translate([roll_diameter/2, 0, 0])
            circle(d=1.2);
            
        // Dispensing slot (front side only)
        translate([0, 0, wall_thickness + roll_length/2])
            hull() {
                translate([0, outer_diameter/2, slot_length/2 - slot_width/2])
                    rotate([90, 0, 0])
                    cylinder(d=slot_width, h=outer_diameter/2 + 1);
                translate([0, outer_diameter/2, -(slot_length/2 - slot_width/2)])
                    rotate([90, 0, 0])
                    cylinder(d=slot_width, h=outer_diameter/2 + 1);
            }
            
        // Finger hole at the bottom to push roll up
        translate([0, 0, -1])
            cylinder(d=15, h=wall_thickness + 2);
    }
}

module dispenser_cap() {
    difference() {
        union() {
            // Cap flange and carabiner loop
            difference() {
                union() {
                    // Flange
                    cylinder(d=outer_diameter, h=wall_thickness);
                    
                    // Carabiner loop extension
                    translate([0, outer_diameter/2 + 4, 0])
                        cylinder(d=16, h=wall_thickness);
                    translate([-8, 0, 0])
                        cube([16, outer_diameter/2 + 4, wall_thickness]);
                }
                // Carabiner hole
                translate([0, outer_diameter/2 + 4, -1])
                    cylinder(d=8, h=wall_thickness + 2);
            }
            
            // Plug with snap fit
            translate([0, 0, wall_thickness])
                difference() {
                    union() {
                        // Main plug body
                        cylinder(d=roll_diameter - 2*tolerance, h=cap_overlap - 1);
                        // Chamfered tip
                        translate([0, 0, cap_overlap - 1])
                            cylinder(d1=roll_diameter - 2*tolerance, d2=roll_diameter - 2*tolerance - 2, h=1);
                    }
                    
                    // Hollow interior of plug
                    translate([0, 0, -1])
                        cylinder(d=roll_diameter - 2*wall_thickness, h=cap_overlap + 2);
                }
                
            // Snap fit ridge
            translate([0, 0, wall_thickness + 4])
                rotate_extrude()
                translate([(roll_diameter - 2*tolerance)/2, 0, 0])
                circle(d=1.2);
        }
        
        // Flex slits to allow the plug to compress during insertion
        translate([0, 0, wall_thickness + 1 + cap_overlap/2]) {
            cube([roll_diameter + 2, 1.5, cap_overlap], center=true);
            cube([1.5, roll_diameter + 2, cap_overlap], center=true);
        }
    }
}