A small but very handy 150mm T-Square for marking parallel lines. Holes/indents are sized for use with a 0.5mm clutch pencil.

I've made it a two part design to make sure that it won't need any supports. The two parts are joined with M3x8 flat head cap screws and the base has openings for a standard M3 nut. The base has a thin layer for support of the holes - these are only 0.2mm thick so easy enough to poke the screw right through it without any cleanup.

Indents are spaced every 5mm and has a legend every 10mm. The holes are spaced at +1, +2, +3 and +4mm. As can be seen from the pictures, it's plenty accurate for woodworking and the two parts are a tight enough fit to get you accurate results without resorting to any kind of calibration. The legend side has indentations but the other side is a plain straight edge to draw straight lines at a 90 degree angle.

The ruler part needs to be flipped upside down for correct print orientation and features multi colour legends if you have a multi colour capable printer. You can of course leave out the multi colour legend and it'll still print fine and you'll still have numbered indentations. Print settings are standard 0.4mm nozzle, 0.2mm layer height. For strength I suggest 3 walls and 25% grid infill.

Enjoy!