This is a ruler foot for free embroidery on a sewing machine. Mine is a Pfaff 1471. I included fusion 360 and step files, so you can adjust it to your machine. Check if the needle is in the center!

I havn't used it with a ruler yet, because I'll lasercut some later, might upload those too (I was thinking not just basic shapes, but also eye shapes, letter shapes or other custom shapes)