8 mm Rod Rolling Parallel Ruler
This 150 mm drafting ruler rolls on a 142 mm piece of 8 mm smooth rod captured inside it, so you can draw evenly spaced parallel lines and hatching without a T-square or drafting board. The rod turns in an 8.3 mm slip-fit tunnel and sticks out about 0.6 mm through a bottom slot. An M3x10 self-tapping screw stops the rod sliding out of the open end. The ruler has bevelled drawing edges on both sides and 10 mm tick notches along one edge.
desk ruler drafting 8mm-rod