// A ruler with scored millimetre ticks and engraved numbers.

/* [Ruler] */
// Measuring length in cm
length_cm = 15; // [5:1:30]
// Ruler width
width = 28; // [18:1:50]
// Engraved label at the right end
label = "KERF"; // 12
// Hole for hanging
hole = true;

/* [Hidden] */
$fn = 40;
lead = 8;
len = length_cm * 10;
total = len + 2 * lead + (hole ? 10 : 0);

difference() {
  rect([total, width], r = 3);
  if (hole) translate([total - 7, width / 2]) circle(d = 5);
}

score() for (mm = [0:len]) let (
  tick = mm % 10 == 0 ? width * 0.42 : mm % 5 == 0 ? width * 0.3 : width * 0.2
) line([lead + mm, width], [lead + mm, width - tick]);

engrave() {
  for (cm = [0:length_cm])
    translate([lead + cm * 10, width * 0.5 - 1]) text(str(cm), 4.2, halign = "center", valign = "top");
  translate([lead + len - 2, 3]) text(label, 3.4, halign = "right", spacing = 1.3);
  translate([lead, 3]) text("cm", 3.4);
}