This triangle ruler is an answer to the constantly breaking corners of plastic set squares which most of us might remember from schooldays. Even when used with a cutter the edges won’t be damaged. The perforation of the sheet metal provides the transparency that is needed when drawing or cutting angles or parallel lines. The set square is made out of stainless steel with precisely etched lines and numbers.

Designer Martha Schwindling developed the idea during her own model-making process for other designs: She makes a lot of paper models and was in need for a tool that’s precise and robust at the same time. While the edges of the plastic set squares were wearing off very quickly when used in combination with a cutter knife, the steel rulers didn’t have the scales for parallels and angles that she needs quite often. The „Steel Triangle” is a combination of both: it’s almost impossible to damage while the perforation makes it transparent: you can easily see through any line or the edge of a paper sheet.

The perforation is a decorative as well as a functional feature, turning a well-known object into something new.

Among the images there is also one showing the design process: Schwindling made a lot of different paper triangles with various perforations in order to find the right pattern.

The „Steel Triangle“ ist distributed through the brand FLAT that Martha Schwindling is running while also working as a designer for other furniture and accessory companies.


the Steel Triangle is transparent because of its perforation so you can see through lines and angles




the  Steel Triangles are distributed through the label FLAT

models of the design process: various perforation patterns were tried out in order to find the right one