$fn = 64;

// --- Parameters ---
tile_size = 100;           // Width and height of the square tile
thickness = 8;             // Total thickness of the tile
dovetail_width = 20;       // Base width of the interlocking dovetail
dovetail_length = 8;       // How far the dovetail extends
tolerance = 0.2;           // Clearance for the dovetail joints
hole_spacing = 5;          // Spacing of the pinboard grid
hole_diameter = 1.5;       // Diameter of the pin holes
grid_limit = 38;           // Extent of the pin hole grid from center
mount_offset = 43;         // Offset for corner mounting holes

// --- Modules ---

// Male dovetail (protrudes outward)
module male_dovetail() {
    linear_extrude(thickness)
    polygon(points=[
        [-dovetail_width/2 + 2, 0],
        [-dovetail_width/2 - 3, dovetail_length],
        [dovetail_width/2 + 3, dovetail_length],
        [dovetail_width/2 - 2, 0]
    ]);
}

// Female dovetail (cuts inward, slightly larger for tolerance)
module female_dovetail() {
    translate([0, 0, -1])
    linear_extrude(thickness + 2)
    polygon(points=[
        [-dovetail_width/2 + 2 - tolerance, -0.1],
        [-dovetail_width/2 - 3 - tolerance, dovetail_length + tolerance],
        [dovetail_width/2 + 3 + tolerance, dovetail_length + tolerance],
        [dovetail_width/2 - 2 + tolerance, -0.1]
    ]);
}

// Main pinboard tile assembly
module modular_pinboard_tile() {
    difference() {
        union() {
            // Base square tile
            translate([-tile_size/2, -tile_size/2, 0])
                cube([tile_size, tile_size, thickness]);

            // Top male dovetail (North)
            translate([0, tile_size/2, 0])
                male_dovetail();
            
            // Right male dovetail (East)
            translate([tile_size/2, 0, 0])
                rotate([0, 0, -90])
                male_dovetail();
        }

        // Bottom female dovetail cutout (South)
        translate([0, -tile_size/2, 0])
            female_dovetail();

        // Left female dovetail cutout (West)
        translate([-tile_size/2, 0, 0])
            rotate([0, 0, -90])
            female_dovetail();

        // Pinboard hole grid
        for(x = [-grid_limit : hole_spacing : grid_limit]) {
            for(y = [-grid_limit : hole_spacing : grid_limit]) {
                translate([x, y, -1])
                    cylinder(d=hole_diameter, h=thickness + 2);
            }
        }
        
        // Corner mounting holes with countersink for screws
        for(x = [-mount_offset, mount_offset]) {
            for(y = [-mount_offset, mount_offset]) {
                // Main screw hole
                translate([x, y, -1])
                    cylinder(d=3.5, h=thickness + 2);
                // Countersink
                translate([x, y, thickness - 2])
                    cylinder(d1=3.5, d2=7.5, h=2.1);
            }
        }
    }
}

// --- Render ---
modular_pinboard_tile();