Trammel

This is a 3D printed rendition of woodworking trammel that can draw circles up to 5 3/4" (about 140mm).
Original wooden version of this can be found here

https://www.pinterest.com/pin/229965124709474743/

You would also need a 1/4" by 2" bolt, butterfly nut and a 4d by 1 1/2" common nail

Designed in QCad and OpenSCAD