$fn=64;

// --- Parameters ---
part_thickness = 20;       // Uniform thickness of the part
holder_inner_dia = 30;     // Diameter of the brush handle
holder_wall = 5;           // Thickness of the holder walls
holder_opening = 22;       // Front opening to snap the brush in

arm_length = 20;           // Distance from wall plate to holder

plate_height = 70;         // Height of the wall plate
plate_thick = 5;           // Thickness of the wall plate

screw_dia = 4.5;           // Diameter of mounting screws
screw_head_dia = 9;        // Diameter of screw head countersink
screw_dist = 46;           // Distance between the two screw holes

// --- Derived Variables ---
holder_outer_dia = holder_inner_dia + (holder_wall * 2);
ring_y = plate_thick + arm_length + holder_outer_dia/2 - 0.5;

// Calculate offset for the front cut to achieve the exact opening width
cut_y_offset = sqrt(pow(holder_inner_dia/2, 2) - pow(holder_opening/2, 2));

// Rotate to lay flat on the side for support-free 3D printing
translate([0, 0, part_thickness/2])
    rotate([0, 90, 0])
        brush_holder();

module brush_holder() {
    difference() {
        union() {
            // Wall Plate (Pill shape)
            hull() {
                translate([0, plate_thick/2, plate_height/2 - part_thickness/2])
                    rotate([90, 0, 0])
                        cylinder(h=plate_thick, d=part_thickness, center=true);
                translate([0, plate_thick/2, -plate_height/2 + part_thickness/2])
                    rotate([90, 0, 0])
                        cylinder(h=plate_thick, d=part_thickness, center=true);
            }

            // Connecting Arm
            translate([0, plate_thick + arm_length/2, 0])
                cube([part_thickness, arm_length + 1, part_thickness], center=true);

            // C-Ring Holder
            translate([0, ring_y, 0])
                cylinder(h=part_thickness, d=holder_outer_dia, center=true);
        }

        // --- Subtractions ---

        // Holder Inner Cutout
        translate([0, ring_y, 0])
            cylinder(h=part_thickness + 2, d=holder_inner_dia, center=true);

        // Holder Front Opening Cut
        translate([0, ring_y + cut_y_offset + holder_outer_dia/2, 0])
            cube([holder_outer_dia + 10, holder_outer_dia, part_thickness + 2], center=true);

        // Screw Holes
        for (z = [screw_dist/2, -screw_dist/2]) {
            // Screw Shaft
            translate([0, -1, z])
                rotate([-90, 0, 0])
                    cylinder(h=plate_thick + 2, d=screw_dia);

            // Screw Countersink
            translate([0, plate_thick + 0.01, z])
                rotate([90, 0, 0])
                    cylinder(h=3, d1=screw_head_dia, d2=screw_dia);
        }
    }
}