Black Forest Pens Rhombus Minimo Fountain Pen - Grey Anodised Aluminium

The Rhombus Minimo is a fountain pen built for carry. At 87 millimeters capped, it fits into a pocket or notebook sleeve without bulk, then extends to a full-sized 117 millimeters when the cap posts onto the back. The aluminum body is anodized in matte grey and weighs just 15 grams, light enough to write with for extended sessions without fatigue.

The barrel surface is machined with a repeating diamond pattern that runs the length of the pen. Each facet is cut into the aluminum, creating a textured grip that keeps the pen secure in your hand without adding rubber or coatings. The pattern also breaks up the smooth metal finish visually, giving the pen a geometric character that sets it apart from plain cylinders.

The cap threads onto the barrel at both ends—close it to protect the nib, or screw it onto the back to balance the pen for writing. The threading is precise and seats firmly without wobbling. Inside, a number 5 steel nib delivers consistent ink flow in either fine or medium line widths. Steel nibs are reliable and straightforward, without the feedback variability of gold.

This is a pen made in Germany by Black Forest Pens, a maker focused on machined metal bodies and functional design. The construction is straightforward: anodized aluminum, steel nib, screw threads. No clip, no decoration beyond the milled pattern. It works as a daily writer or as a backup pen that takes up almost no space in a bag or jacket.