Neat clamshell box. Print-in-place, customizable

/*
 * Clamshell Case with Snap-together Cone Hinge and Two-Dot Snap Clasp
 * Soap-box style rounded case with 45-degree chamfered bottom edges for support-free printing.
 * Designed to be printed flat on the print bed.
 */

/* [Box Dimensions] */
width = 38;           // Closed width (X direction)
length = 38;          // Closed length (Y direction)
base_height = 15;     // Height of the bottom part
lid_height = 6;       // Height of the top part
wall_thickness = 3.0; // Wall thickness of the shell

/* [Hinge Parameters] */
cone_base_radius = 2.5;     // Base radius of the hinge cone
cone_tip_radius = 1.3;     // Tip radius of the hinge cone
cone_height = 2.3;        // Height of the cone protrusion
cone_clearance = 0.26;       // Fit clearance for the socket (increased to prevent fusing)
hinge_axial_clearance = 0.34;// Axial clearance between knuckles (increased to prevent fusing)
hinge_sleeve_radius = 3.6;  // Outer radius of the hinge sleeves
body_clearance = 1.0;        // Clearance between base and lid bodies (increased to prevent rubbing)

/* [Rounding, Chamfer & Fit] */
corner_radius = 6;        // Outer corner rounding radius (XY plane)
chamfer_z = 2.2;          // Bottom edge 45-degree chamfer height (replaces Z rounding for support-free printing)
lip_height = 2.4;         // Height of the alignment collar
collar_clearance = 0.25;  // Clearance for friction fit collar (increased from 0.15)

/* [Clasp Parameters] */
clasp_radius = 0.9;      // Radius of the snap dots (increased by ~30% from 0.8)
clasp_protrusion = 0.5;  // Protrusion height of the dots (increased by ~30% from 0.4)
clasp_clearance = 0.12;   // Fit clearance for the recesses (increased from 0.1)

/* [Debug / Verification] */
render_slice = false;
slice_y = 0;              // Y position for 2D slice analysis
view_mode = "assembly";   // [assembly:Full Assembly, base_only:Base Only, lid_only:Lid Only]
lid_rotation_angle = 0;   // [0:180] - Angle of rotation (0 = open/print position, 180 = closed)

/* [Hidden] */
$fn = 64;
hinge_offset = hinge_sleeve_radius + body_clearance; // 4.6
hinge_axis_z = (base_height + lid_height) / 2; // 10.5mm

// --- Geometry Helper Modules ---

// Base module for the chamfered solid half-box
module chamfered_half_box(w, l, h, r_xy, r_z, is_lid=false) {
    x_min = is_lid ? hinge_offset : -w - hinge_offset;
    x_max = is_lid ? w + hinge_offset : -hinge_offset;
    
    c_x_min = x_min + r_xy;
    c_x_max = x_max - r_xy;
    c_y_min = -l/2 + r_xy;
    c_y_max = l/2 - r_xy;
    
    hull() {
        // Bottom footprint at Z = 0 (shrunk by chamfer_z to form 45-degree chamfer)
        r_bot = r_xy - r_z;
        translate([c_x_min, c_y_min, 0]) cylinder(r=r_bot, h=0.1);
        translate([c_x_max, c_y_min, 0]) cylinder(r=r_bot, h=0.1);
        translate([c_x_max, c_y_max, 0]) cylinder(r=r_bot, h=0.1);
        translate([c_x_min, c_y_max, 0]) cylinder(r=r_bot, h=0.1);
        
        // Full footprint at Z = r_z and above
        translate([c_x_min, c_y_min, r_z]) cylinder(r=r_xy, h=h-r_z);
        translate([c_x_max, c_y_min, r_z]) cylinder(r=r_xy, h=h-r_z);
        translate([c_x_max, c_y_max, r_z]) cylinder(r=r_xy, h=h-r_z);
        translate([c_x_min, c_y_max, r_z]) cylinder(r=r_xy, h=h-r_z);
    }
}

// Inner cavity shape with chamfered bottom matching the external chamfer to maintain constant wall thickness
// Note: h specifies the exact height of the cavity shape.
module inner_cavity(w, l, h, r_xy, t, is_lid=false) {
    x_min = is_lid ? hinge_offset + t : -w - hinge_offset + t;
    x_max = is_lid ? w + hinge_offset - t : -hinge_offset - t;
    y_min = -l/2 + t;
    y_max = l/2 - t;
    
    r_in_xy = max(0.5, r_xy - t);
    
    c_x_min = x_min + r_in_xy;
    c_x_max = x_max - r_in_xy;
    c_y_min = y_min + r_in_xy;
    c_y_max = y_max - r_in_xy;
    
    // To maintain a constant wall thickness of t perpendicular to the 45-degree outer chamfer of height chamfer_z:
    // The inner chamfer height must be max(0, chamfer_z + t * (sqrt(2) - 2)).
    inner_chamfer = max(0, chamfer_z + t * (sqrt(2) - 2));
    r_bot = r_in_xy - inner_chamfer;
    
    hull() {
        // Bottom footprint of cavity at Z = t (shrunk by inner_chamfer)
        translate([c_x_min, c_y_min, t]) cylinder(r=r_bot, h=0.1);
        translate([c_x_max, c_y_min, t]) cylinder(r=r_bot, h=0.1);
        translate([c_x_max, c_y_max, t]) cylinder(r=r_bot, h=0.1);
        translate([c_x_min, c_y_max, t]) cylinder(r=r_bot, h=0.1);
        
        // Full footprint of cavity at Z = t + inner_chamfer and above
        translate([c_x_min, c_y_min, t + inner_chamfer]) cylinder(r=r_in_xy, h=h - (t + inner_chamfer));
        translate([c_x_max, c_y_min, t + inner_chamfer]) cylinder(r=r_in_xy, h=h - (t + inner_chamfer));
        translate([c_x_max, c_y_max, t + inner_chamfer]) cylinder(r=r_in_xy, h=h - (t + inner_chamfer));
        translate([c_x_min, c_y_max, t + inner_chamfer]) cylinder(r=r_in_xy, h=h - (t + inner_chamfer));
    }
}

// --- Main Components ---

module base_part() {
    difference() {
        union() {
            // Main shelled base body (cavity extends 2mm above rim for clean cut)
            difference() {
                chamfered_half_box(width, length, base_height, corner_radius, chamfer_z, is_lid=false);
                inner_cavity(width, length, base_height + 2, corner_radius, wall_thickness, is_lid=false);
            }
            
            // Alignment collar (inner lip)
            // It is wall_thickness/2 thick, on the inner half of the wall, and height lip_height.
            // Exclude it from the back wall.
            difference() {
                // Outer part of lip
                difference() {
                    inner_cavity(width, length, base_height + lip_height, corner_radius, wall_thickness/2, is_lid=false);
                    inner_cavity(width, length, base_height + lip_height + 2, corner_radius, wall_thickness, is_lid=false);
                }
                // Cut off the back wall collar
                translate([-hinge_offset - wall_thickness - 1, -length/2 - 1, base_height - 1])
                    cube([wall_thickness + 2, length + 2, lip_height + 2]);
            }
            
            // Two clasp dots (nubs) on the front collar
            x_collar = -width - hinge_offset + wall_thickness/2;
            x_nub = x_collar - clasp_protrusion + clasp_radius;
            // Position the nub center to maintain exactly 0.4mm solid margin from the top edge of the collar
            clasp_z_offset = lip_height - 0.2 - clasp_radius; 
            z_nub = base_height + clasp_z_offset; 
            
            translate([x_nub, -length/4, z_nub]) sphere(r=clasp_radius);
            translate([x_nub,  length/4, z_nub]) sphere(r=clasp_radius);
        }
        
        // Fingernail recess (capsule-shaped pocket, width increased by 50% to 18mm)
        recess_r = 2.0;
        recess_depth = 1.2; // depth into the 3mm wall (leaves 1.8mm of wall thickness intact)
        recess_width = 18.0;
        y_limit = recess_width/2 - recess_r; // 7.0
        x_recess_center = -width - hinge_offset - (recess_r - recess_depth);
        
        hull() {
            translate([x_recess_center, -y_limit, base_height]) sphere(r=recess_r);
            translate([x_recess_center,  y_limit, base_height]) sphere(r=recess_r);
        }
    }
}


module lid_part() {
    difference() {
        // Main shelled lid body
        difference() {
            chamfered_half_box(width, length, lid_height, corner_radius, chamfer_z, is_lid=true);
            inner_cavity(width, length, lid_height + 2, corner_radius, wall_thickness, is_lid=true);
        }
        
        // Pocket for the base alignment collar
        // The pocket has width wall_thickness/2 + collar_clearance, depth lip_height + collar_clearance.
        // It is subtracted from the inside wall. Exclude back wall.
        difference() {
            difference() {
                inner_cavity(width, length, lid_height + 2, corner_radius, wall_thickness - (wall_thickness/2 + collar_clearance), is_lid=true);
                inner_cavity(width, length, lid_height + 3, corner_radius, wall_thickness, is_lid=true);
            }
            // Protect the back wall from having a pocket
            translate([hinge_offset - 1, -length/2 - 1, -1])
                cube([wall_thickness + 2, length + 2, lid_height + 3]);
        }
        
        // Two clasp recesses (dimples) on the front wall pocket
        x_collar = -width - hinge_offset + wall_thickness/2;
        x_nub = x_collar - clasp_protrusion + clasp_radius;
        x_recess = -x_nub; // symmetric reflection
        // Aligns with the nub center when closed (z_nub = base_height + clasp_z_offset)
        clasp_z_offset = lip_height - 0.2 - clasp_radius; 
        z_recess = lid_height - clasp_z_offset; 
        r_recess = clasp_radius + clasp_clearance;
        
        translate([x_recess, -length/4, z_recess]) sphere(r=r_recess);
        translate([x_recess,  length/4, z_recess]) sphere(r=r_recess);
    }
}

// Module for a base knuckle cylinder, support tab, and external corner chamfers
module base_knuckle(y_s, y_e, add_cone_dir=0) {
    difference() {
        union() {
            // Outer sleeve
            translate([0, y_s, hinge_axis_z])
                rotate([-90, 0, 0])
                    cylinder(r=hinge_sleeve_radius, h=y_e - y_s);
                    
            // Solid tab connecting to base body
            // Base wall is at X = -hinge_offset.
            // The tab is limited in Z range to form a 45-degree support slope (printable without support, no protrusion below chamfer)
            tab_z_min = max(0, hinge_axis_z - hinge_sleeve_radius - hinge_offset);
            hull() {
                translate([0, y_s, hinge_axis_z])
                    rotate([-90, 0, 0])
                        cylinder(r=hinge_sleeve_radius, h=y_e - y_s);
                
                translate([-hinge_offset, y_s, tab_z_min])
                    cube([0.1, y_e - y_s, base_height - tab_z_min]);
            }
        }
        
        // Chamfer cuts on the external corners of the external hinge arms
        cut_size = 3.2; // depth of cut at the sleeve end
        theta = atan(cut_size / (hinge_sleeve_radius + hinge_offset)); // angle of slice
        
        if (add_cone_dir == 1) {
            // Left knuckle: diagonal slice from [-hinge_offset, y_s] to [hinge_sleeve_radius, y_s + cut_size]
            translate([-hinge_offset, y_s, hinge_axis_z])
                rotate([0, 0, theta])
                    translate([0, -20, -20])
                        cube([25, 20, 40]);
        } else if (add_cone_dir == -1) {
            // Right knuckle: diagonal slice from [-hinge_offset, y_e] to [hinge_sleeve_radius, y_e - cut_size]
            translate([-hinge_offset, y_e, hinge_axis_z])
                rotate([0, 0, -theta])
                    translate([0, 0, -20])
                        cube([25, 20, 40]);
        }
    }
    
    // Cone protrusion (keep outside difference to ensure cone geometry is untouched)
    if (add_cone_dir == 1) {
        translate([0, y_e, hinge_axis_z])
            rotate([-90, 0, 0])
                cylinder(r1=cone_base_radius, r2=cone_tip_radius, h=cone_height);
    } else if (add_cone_dir == -1) {
        translate([0, y_s, hinge_axis_z])
            rotate([90, 0, 0])
                cylinder(r1=cone_base_radius, r2=cone_tip_radius, h=cone_height);
    }
}

// Module for a lid knuckle cylinder, support tab, and internal sockets 
module lid_knuckle(y_s, y_e, add_sockets=false) {
    difference() {
        union() {
            // Outer sleeve cylinder
            translate([0, y_s, hinge_axis_z])
                rotate([-90, 0, 0])
                    cylinder(r=hinge_sleeve_radius, h=y_e - y_s);
                    
            // Support tab connecting to lid body 
            // Lid wall is at X = hinge_offset.
            // The tab is limited in Z range to avoid extending below the flat portion of the wall (starts at chamfer_z).
            tab_z_min = chamfer_z;
            hull() {
                translate([0, y_s, hinge_axis_z])
                    rotate([-90, 0, 0])
                        cylinder(r=hinge_sleeve_radius, h=y_e - y_s);
                
                translate([hinge_offset , y_s, tab_z_min])
                    cube([0.1, y_e - y_s, lid_height - tab_z_min]);
            }
        }
        
        if (add_sockets) {
            // Socket at y_s (pointing +Y)
            translate([0, y_s - 0.1, hinge_axis_z])
                rotate([-90, 0, 0])
                    cylinder(r1=cone_base_radius + cone_clearance, r2=cone_tip_radius + cone_clearance, h=cone_height + cone_clearance + 0.1);
            
            // Socket at y_e (pointing -Y)
            translate([0, y_e + 0.1, hinge_axis_z])
                rotate([90, 0, 0])
                    cylinder(r1=cone_base_radius + cone_clearance, r2=cone_tip_radius + cone_clearance, h=cone_height + cone_clearance + 0.1);
        }
    }
}

module base_hinge_assembly() {
    hinge_L = length - 2 * corner_radius;
    
    // Segment 1 (Base, left) - 35% narrower (nominal width = 0.275 * hinge_L)
    y1_s = -hinge_L/2;
    y1_e = -hinge_L * 0.225;
    base_knuckle(y1_s, y1_e, add_cone_dir=1);
    
    // Segment 3 (Base, right) - 35% narrower (nominal width = 0.275 * hinge_L)
    y3_s = hinge_L * 0.225;
    y3_e = hinge_L/2;
    base_knuckle(y3_s, y3_e, add_cone_dir=-1);
}

module lid_hinge_assembly() {
    hinge_L = length - 2 * corner_radius;
    
    // Segment 2 (Lid, middle) - 35% wider (nominal width = 0.45 * hinge_L)
    y2_s = -hinge_L * 0.225 + hinge_axial_clearance;
    y2_e = hinge_L * 0.225 - hinge_axial_clearance;
    lid_knuckle(y2_s, y2_e, add_sockets=true);
}

// --- Assembly and Render Modes ---

module lid_assembly() {
    translate([0, 0, hinge_axis_z])
        rotate([0, -lid_rotation_angle, 0])
            translate([0, 0, -hinge_axis_z]) {
                union() {
                    lid_part();
                    lid_hinge_assembly();
                }
            }
}

module full_model() {
    if (view_mode == "base_only") {
        union() {
            base_part();
            base_hinge_assembly();
        }
    } else if (view_mode == "lid_only") {
        lid_assembly();
    } else {
        union() {
            base_part();
            base_hinge_assembly();
        }
        lid_assembly();
    }
}

// Render logic
if (render_slice) {
    // 2D projection slicing mode
    // To inspect the X-Z cross section at y = slice_y:
    // We translate the model along Y so that y = slice_y is at Y = 0.
    // Then we rotate 90 degrees around the X-axis so the X-Z plane aligns with the X-Y plane.
    // Then we apply projection(cut = true).
    projection(cut = true)
        rotate([90, 0, 0])
            translate([0, -slice_y, 0])
                full_model();
} else {
    // Normal 3D model
    // We instantiate the base and lid groups directly at the top level
    // to allow --enable lazy-union to export them as separate objects.
    if (view_mode == "base_only") {
        union() {
            base_part();
            base_hinge_assembly();
        }
    } else if (view_mode == "lid_only") {
        lid_assembly();
    } else {
        // Base object group
        union() {
            base_part();
            base_hinge_assembly();
        }
        // Lid object group
        lid_assembly();
    }
}