I would take some scrap fabric, cut your 3.5" squares. Will you be setting them on point?? If so, you will have to determine the size of those triangles. The finished size of a 3" square set on point should give yo a border width of just a hair under 4.25". Photos always help us see what you are seeing and is easier to give advice. Good Luck !
Last edited by ManiacQuilter2; 12-10-2014 at 05:39 AM.