$fn=64;

// --- Parameters ---
jar_diameter = 55;       // Inner diameter of the treat jar cup
jar_depth = 40;          // Inner depth of the cup
wall_thickness = 3;      // Thickness of the walls

rail_thickness = 6;      // Thickness of the rail to clip over
hook_drop = 25;          // Downward length of the attachment hook
clip_width = 30;         // Width of the hook
retaining_lip = 1.5;     // Size of the snap-fit lip on the hook

// --- Calculated Variables ---
cup_outer_d = jar_diameter + wall_thickness * 2;
cup_outer_h = jar_depth + wall_thickness;
mount_y = cup_outer_d / 2 - 10;
hook_outer_y = cup_outer_d / 2 + rail_thickness + wall_thickness;
hook_length = hook_outer_y - mount_y;

// --- Module ---
module treat_jar_holder() {
    difference() {
        union() {
            // Main Cup Outer Shell
            cylinder(d=cup_outer_d, h=cup_outer_h);
            
            // Rail Attachment
            translate([-clip_width/2, 0, 0]) {
                // Top overhang connecting cup to hook
                translate([0, mount_y, cup_outer_h - wall_thickness])
                    cube([clip_width, hook_length, wall_thickness]);
                
                // Solid mount block merging into the cup cylinder
                translate([0, mount_y, cup_outer_h - hook_drop])
                    cube([clip_width, 10, hook_drop]);
                
                // Downward hook
                translate([0, cup_outer_d/2 + rail_thickness, cup_outer_h - hook_drop])
                    cube([clip_width, wall_thickness, hook_drop]);
                    
                // Retaining lip for secure rail attachment
                translate([0, cup_outer_d/2 + rail_thickness - retaining_lip, cup_outer_h - hook_drop])
                    cube([clip_width, retaining_lip, wall_thickness]);
            }
        }
        
        // Hollow out the cup (also clears out overlapping attachment geometry)
        translate([0, 0, wall_thickness])
            cylinder(d=jar_diameter, h=jar_depth + 1);
    }
}

// --- Render ---
treat_jar_holder();