geometric pen

noun2

1. •
   A configurable drawing tool for creating lines that has a width specified in logical units, as opposed to device units (pixels), and therefore scales when the resulting image is zoomed in or out.

   • To be more specific, a geometric pen has a scalable width, different styles, end caps, and joins. — 2001
2. •
   An instrument for drawing geometric curves, in which the movements of a pen or pencil attached to a revolving arm of adjustable length may be indefinitely varied by changing the toothed wheels which give motion to the arm.

   • But it may be proper to take some notice of the geometric pen, as it is not so well known , nor the principles on which it depends so obvious . — 1797