A small pen you could attach to "Flying tiger Copenhagen" notebook and carry with you.
The need for this came with an idea for very small EDC notebook , buisness card sized .
Printed on prusa MINI with Recycled PLA from Fiberlogy.
The model consist of a Pen itself and small cap - you need to get a insert yourself.
As a bonus - I attached a simple .STEP file with the pen.
The author hasn't provided the model origin yet.