$fn = 64;

// --- Parameters ---
mount_width = 90;       // Total width of the wall mount
mount_height = 110;     // Total height of the wall plate
wall_thickness = 8;     // Thickness of the back plate
arm_length = 80;        // Length of the support arms (fits standard packing tape guns)
arm_thickness = 20;     // Width of each support arm
support_drop = 80;      // 45-degree overhang drop for support-free 3D printing
lip_height = 15;        // Height of the front retaining lip
screw_d = 5.5;          // Diameter of the screw shaft
screw_head_d = 12;      // Diameter of the screw head

difference() {
    union() {
        // Back wall plate
        cube([mount_width, wall_thickness, mount_height]);

        // Left Arm
        translate([0, 0, 0]) arm();

        // Right Arm
        translate([mount_width - arm_thickness, 0, 0]) arm();
    }

    // --- Screw Holes ---
    // Top screw hole (centered between arms)
    translate([mount_width / 2, -1, mount_height - 15])
        screw_hole();

    // Bottom screw hole (centered below arms)
    translate([mount_width / 2, -1, 15])
        screw_hole();
}

module arm() {
    union() {
        // Main arm with 45-degree triangular support for support-free printing
        hull() {
            // Top horizontal section
            translate([0, 0, mount_height - arm_thickness])
                cube([arm_thickness, wall_thickness + arm_length, arm_thickness]);
            // Wall support base
            translate([0, 0, mount_height - arm_thickness - support_drop])
                cube([arm_thickness, wall_thickness, 0.1]);
        }

        // End lip to prevent the dispenser from sliding off
        translate([0, arm_length, mount_height - arm_thickness])
            cube([arm_thickness, wall_thickness, arm_thickness + lip_height - wall_thickness/2]);

        // Rounded top of the lip
        translate([0, arm_length + wall_thickness/2, mount_height + lip_height - wall_thickness/2])
            rotate([0, 90, 0])
            cylinder(d=wall_thickness, h=arm_thickness);
    }
}

module screw_hole() {
    rotate([-90, 0, 0]) {
        // Shaft clearance
        cylinder(d=screw_d, h=wall_thickness + 2);
        
        // Screw head recess
        translate([0, 0, wall_thickness - 2])
            cylinder(d=screw_head_d, h=5);
            
        // Printable chamfer for screw head
        translate([0, 0, wall_thickness - 2 - (screw_head_d - screw_d)/2])
            cylinder(d1=screw_d, d2=screw_head_d, h=(screw_head_d - screw_d)/2 + 0.01);
    }
}