Working with Figures > 2D Figures > Editing 2D Figures > Editing Tools for 2D Figures > Switching Pens
  
Switching Pens
Pens are a defined as a collection of attributes that are applied to lines; such as style, color, and thickness. You can use different pens to draw lines, polylines, ellipses, and beziers, or apply a different pen to an existing line.
Pen are set in the Creo Illustrate Options dialog box. For more information on defining pens and the Pens Palette, see About Pens.
Switching Pens
Toggle between Thick and Thin pens using the Switch Pens tool.
1. Select one or more lines to edit.
2. Toggle Switch Pens to change pens.
* 
Alternatively, you can double click a line to switch pens.