An accessory for ink drafting pens that allow parallel curved ink lines to be drawn. The accessory is a guide for use with a conventional template. The accessory has a circular outer surface for rolling contact with the edge of the template. It also has an axial passage for receiving the tubular tip of a conventional drawing pen. The passage is larger than the tip, allowing the guide to tilt toward the template. This provides a clearance between the bottom of the guide and the line being drawn to avoid smearing. The guide's height is selected so that its top slidingly contacts the collar of the pen to limit the amount of tilt.