Only two elements are required to be made for the compass ruler these are made to fit a 12mm x ~0.5mm steel ruler These are the pivot element and the slider which holds the pencil and are designed to be 3D printed. Both elements have a slot which is compatible with the ruler allowing them to slide up and down. The pivot element sits at the end of the ruler and is held in place with a screw, a hole at the extreme is the pivot point. This point has two options. 1: Fixed with a grub screw that will be the circle centre. 2: Placed over a fixed point (i.e. Nail), that is the centre of the circle to be drawn. For greater flexibility two pivot elements can be made for interchangeability subject to requirements simply swapping the elements as required for the task. The slider that holds the pencil needs to be able to slide up and down the ruler and locked in placed with a thumb screw at the required point to set the circle radius. Screw holes are M3 Thumb screws - 10mm in length The design would be created using BlocksCAD. The orientation of the elements in relation to the bed is critical as a result of the slots and the impact of gravity. As a result the slots are orientation vertically and short arcs are used in non supportive horizontal runs to eliminate sagging. Due to the small size of the elements and that they will have threaded bolts fitted the infill was set at 100% to add strength. Basic settings: Layer Height - 0.15mm Infill type - Tri-Hexagon Base adhesion - Brim Filament - PLA Size 13 x 19 x 29 mm Weight - 6g Filament length - 2m Print time - 1hr 20min