The purpose of this tool is to make it easier to draw perpendicular lines an the faces of a wood beam that are accurately co-planar, which is sometimes difficult when the edges are beveled or missing, as sometimes happens in carpentry.

It also serves as a metric ruler, though the embossed graduation may not be very sharp. Measurements start from the edge.

To make it easy to carry, the two halves can be joined thanks to a robust hinge, which uses the generic design that I published previously: https://www.printables.com/model/297906-vertical-customizable-hinge

It should be printed in place vertically, with a small support for the first hinge buckle. Remember that the square angles will only be as accurate as the printer axis perpendicularity !

The hinge is optimized for a 0.15 layer height, and 0.8mm wall thickness (or more). A brim is strongly advised to avoid warping as the object is large but surface contact is very low. The downside is that the graduations won't look as nice with a brim.

The original version has a leaf width of 214mm, with numbers going up to 20cm. I added a slightly smaller version with 200mm wide leaves which should be easier to fit on a print bed. The OpenSCAD file can also be customized to generate other sizes, changing the global variables n, w, numbers, and the upper bound of the graduation ranges [1:numbers*10+13] and [1:numbers*2+2] (I didn't make the effort to minimize the number of parameters). Rendering will take a loooong time !