I just finished my new little compass.
It's 2 meters radius, the long rod is a square 20x3mm tube, punched every 5cm, the cursor is from square25x2mm, with a little window for the scale, double M10 screws as fasteners. Chalk holder with 11mm hole, M6 thread, from a 40mm round bar. Base frame is a 30mm thick aluminum, with index and three different points. Main shaft is a 18mm, M12, I built also a spacer and a lock.
I used 2,5mm electrodes, stick welding, 60A, AC.
The trace is very good, I wanted a tool pretty stable and easy to use. Cutting large things is not easy, having a bad pattern is even worst!
Due to material, it would be perfect even with a cutting torch, adding a dedicated support.