This is one among the traditional ruling pens made in Germany that graphic designers used for technical drawing., Nowadays we have many more ruling
Quick Guide: How to use a Ruling Pen — Jeea Mirza
Ruling Pen Basics John Neal Books Blog
About the Ruling pen – Handwritmic
Christopher Haanes Calligraphy / Lettering / Book design
Special Pen Set
Elegant Special Penholders
Pens National Museum of American History
Special Pen Set
Detachable Nibs for attaching to drafting compasses with breakable legs., Perfect Calligraphy Tool; small point alternative to using a fountain pen.,
Pacific Arc, Ruling Pen: with handle
Hand made ruling pen for expressive calligraphy/Gold or silver/2
Haff Ruling pen
Alvin Professional 5.5 Oval Nib Ruling Pen
4x Artist Ruling Pen Masking Fluid Fine Line Adjustable Writing
Ruling Pen Special Set 3 Herramientas Caligráficas Rolfpens