Custom text keychain generator

/* [Text Settings] */

// The text to display on the label
label_text = "HelloWorld";

// Font name (ensure it is installed on your system)
font_name = "Liberation Sans:style=Bold Italic"; // font

// Font size in mm
font_size = 20; // [10:1:100]

// Letter spacing multiplier
letter_spacing = 1; // [0.5:0.05:2.0]

/* [Keychain Loop Settings] */

// Position of the keychain loop
keychain_position = "left"; // [none: None, top: Top, left: Left]

// Diameter of the hole inside the keychain loop (mm)
keychain_hole_diameter = 4; // [2.0:0.5:15.0]

// Extra outer ring margin thickness around the hole (mm)
keychain_ring_thickness = 3; // [1.0:0.5:10.0]

// Manual X-axis offset adjustment for the loop (mm)
keychain_offset_x = -28; // [-100:1:100]

// Manual Y-axis offset adjustment for the loop (mm)
keychain_offset_y = 0; // [-100:1:100]

/* [Layer Thicknesses] */

// Height of the bottom-most background layer (mm)
base_height = 2; // [0.5:0.1:10.0]

// Height of the middle border layer (mm)
middle_height = 1.2; // [0.2:0.1:5.0]

// Height of the top text layer (mm)
top_height = 1.2; // [0.2:0.1:5.0]

/* [Offsets] */

// Outer border offset width (mm)
base_offset = 6; // [1.0:0.1:15.0]

// Inner border offset width (mm)
middle_offset = 3.5; // [0.5:0.1:10.0]

/* [Output Settings] */

// Choose what to render (for exporting separate STLs/3MF parts)
render_mode = "all"; // [all: All Layers, base: Base Only, middle: Middle Only, top: Top Only]

/* [Quality] */

// Resolution of the rounded offsets
$fn = 32; // [16:1:128]

/* [Hidden] */
epsilon = 0.01;

// Approximate text boundary dimensions for loop positioning
char_count = len(label_text);
approx_width = char_count * font_size * 0.45 * letter_spacing;
approx_height = font_size * 0.75;

// Determine automatic base alignment coordinates
auto_x = (keychain_position == "left") ? -(approx_width / 2 + base_offset) : 0;
auto_y = (keychain_position == "top") ? (approx_height / 2 + base_offset) : 0;

loop_x = auto_x + keychain_offset_x;
loop_y = auto_y + keychain_offset_y;

module text_shape() {
    text(
        text = label_text, 
        font = font_name, 
        size = font_size, 
        spacing = letter_spacing, 
        halign = "center", 
        valign = "center"
    );
}

module base_layer() {
    difference() {
        linear_extrude(height = base_height) {
            union() {
                offset(r = base_offset) {
                    text_shape();
                }
                if (keychain_position != "none") {
                    translate([loop_x, loop_y]) {
                        circle(d = keychain_hole_diameter + 2 * keychain_ring_thickness);
                    }
                }
            }
        }
        if (keychain_position != "none") {
            translate([loop_x, loop_y, -epsilon]) {
                cylinder(h = base_height + 2 * epsilon, d = keychain_hole_diameter);
            }
        }
    }
}

module middle_layer() {
    translate([0, 0, base_height]) {
        linear_extrude(height = middle_height) {
            offset(r = middle_offset) {
                text_shape();
            }
        }
    }
}

module top_layer() {
    translate([0, 0, base_height + middle_height]) {
        linear_extrude(height = top_height) {
            text_shape();
        }
    }
}

// Render logic
if (render_mode == "all") {
    color("White") base_layer();
    color("Black") middle_layer();
    color("Red") top_layer();
} else if (render_mode == "base") {
    base_layer();
} else if (render_mode == "middle") {
    middle_layer();
} else if (render_mode == "top") {
    top_layer();
}