As my quilt guild members will be making a quilt using this square, I thought I'd make a tutorial for their benefit.
You need 2 fabrics for this project. The center square is out of unbleached muslin. You will be able to write a message on this square.
Cut it at 4 3/4"
Cut 2-4" squares out of the other fabric.
And then cut them in half diagonally one time. You will have 4 half square triangles.
Center one of the half square triangles on the square. Make sure the point is in the center.
Sew it. Then do the same thing on the other side. It should look like this.
Press the seams toward the outside.
Now you have 2 sides finished. Do the same thing with the other 2 sides.
What a busy background I have on my ironing board!
And here is your completed square at 6 1/2" after trimming. That wasn't too hard, was it?