These are quilting squares I made for a friend and are similar to a Bloc Loc. They have a 0.3" wide relief for a stitch from corner to corner. To be honest, I don't know anything about stitching and made these upon request. The real deal can be found at http://www.blocloc.com/ and are pretty high quality, incremented, and transparent.
EDIT Units in inches. If you slice with mm, you will need to scale by 25.4x
5_squared.stl | 1.3KB |