$fn=64;

// --- Parameters ---
length_units = 5;       // Number of Gridfinity units long
width_units = 1;        // Number of Gridfinity units wide (1 for a standard rail)
grid_size = 42;         // Standard Gridfinity unit size
base_height = 5.0;      // Height of the rail base
screw_hole_dia = 3.5;   // Diameter of mounting screw shaft (M3 standard)
screw_head_dia = 8.0;   // Diameter of countersink head
screw_head_height = 3.0;// Height of countersink

// --- Calculated Variables ---
rail_length = length_units * grid_size;
rail_width = width_units * grid_size;

module rounded_square(size, radius, h) {
    hull() {
        for (x = [-size[0]/2 + radius, size[0]/2 - radius]) {
            for (y = [-size[1]/2 + radius, size[1]/2 - radius]) {
                translate([x, y, 0]) cylinder(r=radius, h=h);
            }
        }
    }
}

module gridfinity_plug() {
    plug_w1 = 41.5;
    plug_r1 = 4.0;
    plug_w2 = 37.9;
    plug_r2 = 2.2;

    translate([0, 0, base_height - 0.01]) {
        // Lower straight section
        rounded_square([plug_w1, plug_w1], plug_r1, 0.81);

        // Chamfered middle section
        translate([0, 0, 0.8])
        hull() {
            rounded_square([plug_w1, plug_w1], plug_r1, 0.01);
            translate([0, 0, 1.8]) rounded_square([plug_w2, plug_w2], plug_r2, 0.01);
        }

        // Upper straight section
        translate([0, 0, 2.6])
        rounded_square([plug_w2, plug_w2], plug_r2, 1.8);
    }
}

module gridfinity_rail() {
    difference() {
        // Main Body
        union() {
            // Base strip
            translate([rail_length/2, rail_width/2, base_height/2])
                cube([rail_length, rail_width, base_height], center=true);

            // Gridfinity Plugs
            for (x = [0 : length_units - 1]) {
                for (y = [0 : width_units - 1]) {
                    translate([x * grid_size + grid_size/2, y * grid_size + grid_size/2, 0])
                        gridfinity_plug();
                }
            }
        }

        // Mounting Holes
        for (x = [0 : length_units - 1]) {
            for (y = [0 : width_units - 1]) {
                translate([x * grid_size + grid_size/2, y * grid_size + grid_size/2, 0]) {
                    // Screw shaft
                    translate([0, 0, -1])
                        cylinder(d=screw_hole_dia, h=base_height + 10);
                    
                    // Countersink
                    translate([0, 0, base_height - screw_head_height])
                        cylinder(d1=screw_hole_dia, d2=screw_head_dia, h=screw_head_height + 0.02);
                    
                    // Clearance for screw head through the plug
                    translate([0, 0, base_height])
                        cylinder(d=screw_head_dia, h=10);
                }
            }
        }
    }
}

gridfinity_rail();