Trammel Points

thingiverse

To draw an accurate large circle, utilize trammel points by connecting them to a 10mm square metal or wooden bar. Set the distance equal to your desired circle's radius, then scribe it. For this, print two trammel point designs, partially drill through a 3mm hole and insert a sharpened steel bit, cut-off screw or any fitting piece. However, don't fully drill through. Clean out the square holes for a tight fit on your chosen rod. Finally, slide the points onto the rod, adjust their distance, and secure them with M3 setscrews.