difference() {
    cube([93.75+6,254+6,5]);
    translate([3,3,0]) {
        for (j = [0:4]) {
            for (i = [0:13]) {
                translate([j*(15+4.5),i*(14+4.5),0]) translate([-(.75/2),-(.75/2),0]) cube([15.75,14.75,10]);
            }
        }    
    }
}