Builds / Lars Zimmermann / Open Design Pen / Other · March 7, 2023


The O:pen is a simple but effective pen by the designer Lars Zimmermann. It comes with a special circular skill: Regular pens are usually designed for one type of refill. O:pen connects to all available refills; reuse made easy. 

↓ makes  *


This pen can hold different kinds of refills. The inner tube has an insert thread to lock the refill in place with a standard set screw.
Aluminium engraved.
A piece of silicone tube…
added as cap.

Available now

Design info

  • “It happened to most of us: Our favourite ball point pen is suddenly out of ink. We search for another ball point pen to swap the refill. Only to discover: the refills are different. The new one does not fit. Well if PenOpen is your favourite pen this won’t happen again.”
  • Above you can see a picture where a cap is added. The cap is just a small piece of silicone tube. The cap is not part of Trikkas parts catalog. 
  • Please visit the original post by the designer to learn more about Penopen and how to make it and to see iterations of it. Initial post backup.pdf
  • Pictures by Mifactori, CC-BY-4.0
  • Disclaimer