This tool allows you to mark a precision parallel line up to 10CM away from an edge. 

Print Instructions:

Print the “Rule” with supports on, and optionally add a filament color change to highlight the text.

Print the “Bar”

Assemble the two together with superglue, or optional screws. 

Usage:

To mark a line of “3.4mm”, find the hole nearest the “3”, and then count up and to the right until you're on the fourth hole. Then insert your pencil, and slide the bar across the reference edge.