I noticed my teacher using a special tool to check the straightness and distance of sewing lines on leather projects. I liked the idea so much that I took a photo and printed a few versions on my 3D printer. It is a very handy way to make sure the stitches stay a perfect distance from the edge of the material. I did not see these tools being used during my internships and I am curious if they are common in the craft. It might be something more popular in large factories where every piece must be identical. But for me it provides a nice sense of consistency and helps me keep my work looking professional.