Writing has always been influenced by the tools we use. It can be a broad nib pen, a brush or a typewriter. It’s fascinating to look closer at how these devices work, and what in their construction, or in the way we use them, influences the form of the letters. Here, we will review the Tecnostyl Lettering Set, manufactured in the 1970s, an instrument used to draw technical, engineered letters. This genre started to become popular at the beginning of the 20th century, reflecting the sense of order and rationality that was looked for in architecture, design and engineering. There was a higher demand of precision and consistency, and new tools appeared that helped to standardise lettering. Before, text complementing a plan, or the section of an object, was handwritten in a variety of styles, often decorative, not fit for the industrial world that was being built.