Dezeen’s Alice Morby shares a retractable, refillable pen designed by Japanese architect Shigeru Ban for Acme Studio.

The three-sided tool features a laser-etched ruler on each of its surfaces, functioning as an architect’s scale ruler as well as a ballpoint pen. The pen retails for $90, and is currently available for pre-order on the Acme Studio web store.

The instruments typically feature multiple scales along its length, so architects can measure different drawings with the same ruler. To fit various scales onto one piece of equipment, designs are often tetrahedral – a feature that Ban replicated for his pen.

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